diff --git a/InternalUtilities/Accounts.cs b/InternalUtilities/Accounts.cs
index 9fb5862a..fcb32a9a 100644
--- a/InternalUtilities/Accounts.cs
+++ b/InternalUtilities/Accounts.cs
@@ -1,5 +1,6 @@
 using System;
 using System.Collections.Generic;
+using System.Linq;
 using AudibleApi;
 using AudibleApi.Authorization;
 using Dinah.Core;
@@ -28,7 +29,12 @@ namespace InternalUtilities
 	{
 		public event EventHandler Updated;
 		private void update(object sender = null, EventArgs e = null)
-			=> Updated?.Invoke(this, new EventArgs());
+		{
+			foreach (var account in AccountsSettings)
+				validate(account);
+			update_no_validate();
+		}
+		private void update_no_validate() => Updated?.Invoke(this, new EventArgs());
 
 		public Accounts() { }
 
@@ -45,15 +51,13 @@ namespace InternalUtilities
 			// 'set' is only used by json deser
 			set
 			{
-				_accountsSettings_backing = value;
-
-				if (_accountsSettings_backing is null)
+				if (value is null)
 					return;
 
-				foreach (var acct in _accountsSettings_backing)
-					acct.Updated += update;
+				foreach (var account in value)
+					_add(account);
 
-				update();
+				update_no_validate();
 			}
 		}
 		[JsonIgnore]
@@ -66,29 +70,78 @@ namespace InternalUtilities
 		public string ToJson(Formatting formatting = Formatting.Indented)
 			=> JsonConvert.SerializeObject(this, formatting, Identity.GetJsonSerializerSettings());
 
-public void UNITTEST_Seed(Account account)
+		public void Add(Account account)
 		{
-			_accountsSettings_backing.Add(account);
-			update();
+			_add(account);
+			update_no_validate();
 		}
 
-		// replace UNITTEST_Seed
+		public void _add(Account account)
+		{
+			validate(account);
 
-		// when creating Account object (get, update, insert), subscribe to it's update. including all new ones on initial load
-		// removing: unsubscribe
+			_accountsSettings_backing.Add(account);
+			account.Updated += update;
+		}
 
-		// IEnumerable<Account> GetAllAccounts
+		// more common naming convention alias for internal collection
+		public IReadOnlyList<Account> GetAll() => AccountsSettings;
 
-		// void UpsertAccount (id, locale)
-		//   if not exists
-		//     create account w/null identity
-		//     save in file
-		//   return Account?
-		//   return bool/enum of whether is newly created?
+		public Account GetAccount(string accountId, string locale)
+		{
+			if (locale is null)
+				return null;
 
-		// how to persist edits to [Account] obj?
-		//   account name, decryptkey, id tokens, ...
-		//   persistence happens in [Accounts], not [Account]. an [Account] accidentally created directly shouldn't mess up expected workflow ???
+			return AccountsSettings.SingleOrDefault(a => a.AccountId == accountId && a.IdentityTokens.Locale.Name == locale);
+		}
+
+		public Account Upsert(string accountId, string locale)
+		{
+			var acct = GetAccount(accountId, locale);
+
+			if (acct != null)
+				return acct;
+
+			var l = Localization.Locales.Single(l => l.Name == locale);
+			var id = new Identity(l);
+
+			var account = new Account(accountId) { IdentityTokens = id };
+			Add(account);
+			return account;
+		}
+
+		public bool Delete(Account account)
+		{
+			if (!_accountsSettings_backing.Contains(account))
+				return false;
+
+			account.Updated -= update;
+			return _accountsSettings_backing.Remove(account);
+		}
+
+		public bool Delete(string accountId, string locale)
+		{
+			var acct = GetAccount(accountId, locale);
+			if (acct is null)
+				return false;
+			return Delete(acct);
+		}
+
+		private void validate(Account account)
+		{
+			ArgumentValidator.EnsureNotNull(account, nameof(account));
+
+			var accountId = account.AccountId;
+			var locale = account?.IdentityTokens?.Locale?.Name;
+
+			var acct = GetAccount(accountId, locale);
+
+			if (acct is null || account is null)
+				return;
+
+			if (acct != account)
+				throw new InvalidOperationException("Cannot add an account with the same account Id and Locale");
+		}
 	}
 	public class Account : Updatable
 	{
diff --git a/_Tests/InternalUtilities.Tests/AccountTests.cs b/_Tests/InternalUtilities.Tests/AccountTests.cs
index 85ea943d..5e5cba53 100644
--- a/_Tests/InternalUtilities.Tests/AccountTests.cs
+++ b/_Tests/InternalUtilities.Tests/AccountTests.cs
@@ -10,6 +10,7 @@ using AudibleApi;
 using AudibleApi.Authorization;
 using Dinah.Core;
 using FluentAssertions;
+using FluentAssertions.Common;
 using InternalUtilities;
 using Microsoft.VisualStudio.TestPlatform.Common.Filtering;
 using Microsoft.VisualStudio.TestTools.UnitTesting;
@@ -133,7 +134,7 @@ namespace AccountsTests
         }
     }
 
-    public class AccountsPersisterTestBase
+    public class AccountsTestBase
     {
         protected string TestFile;
 
@@ -153,7 +154,7 @@ namespace AccountsTests
     }
 
     [TestClass]
-    public class ctor : AccountsPersisterTestBase
+    public class ctor : AccountsTestBase
     {
         [TestMethod]
         public void create_file()
@@ -190,8 +191,8 @@ namespace AccountsTests
         public void save_multiple_children()
         {
             var accounts = new Accounts();
-            accounts.UNITTEST_Seed(new Account("a0") { AccountName = "n0" });
-            accounts.UNITTEST_Seed(new Account("a1") { AccountName = "n1" });
+            accounts.Add(new Account("a0") { AccountName = "n0" });
+            accounts.Add(new Account("a1") { AccountName = "n1" });
 
             // dispose to cease auto-updates
             using (var p = new AccountsPersister(accounts, TestFile)) { }
@@ -209,7 +210,7 @@ namespace AccountsTests
             var idJson = JsonConvert.SerializeObject(id, Identity.GetJsonSerializerSettings());
 
             var accounts = new Accounts();
-            accounts.UNITTEST_Seed(new Account("a0") { AccountName = "n0", IdentityTokens = id });
+            accounts.Add(new Account("a0") { AccountName = "n0", IdentityTokens = id });
 
             // dispose to cease auto-updates
             using (var p = new AccountsPersister(accounts, TestFile)) { }
@@ -222,7 +223,7 @@ namespace AccountsTests
     }
 
     [TestClass]
-    public class save : AccountsPersisterTestBase
+    public class save : AccountsTestBase
     {
         // add/save account after file creation
         [TestMethod]
@@ -238,7 +239,7 @@ namespace AccountsTests
                 var idIn = new Identity(localeIn);
                 var acctIn = new Account("a0") { AccountName = "n0", IdentityTokens = idIn };
 
-                p.Accounts.UNITTEST_Seed(acctIn);
+                p.Accounts.Add(acctIn);
             }
 
             // re-load file. ensure account still exists
@@ -266,7 +267,7 @@ namespace AccountsTests
                 var idIn = new Identity(localeIn);
                 var acctIn = new Account("a0") { AccountName = "n0", IdentityTokens = idIn };
 
-                p.Accounts.UNITTEST_Seed(acctIn);
+                p.Accounts.Add(acctIn);
             }
 
             // re-load file. ensure account still exists
@@ -286,7 +287,7 @@ namespace AccountsTests
                 var idIn = new Identity(localeIn);
                 var acctIn = new Account("a1") { AccountName = "n1", IdentityTokens = idIn };
 
-                p.Accounts.UNITTEST_Seed(acctIn);
+                p.Accounts.Add(acctIn);
             }
 
             // re-load file. ensure both accounts still exist
@@ -304,6 +305,32 @@ namespace AccountsTests
             }
         }
 
+        [TestMethod]
+        public void update_Account_field_just_added()
+        {
+            // create initial file
+            using (var p = new AccountsPersister(new Accounts(), TestFile)) { }
+
+            // load file. create 2 accounts
+            using (var p = new AccountsPersister(TestFile))
+            {
+                var locale1 = Localization.Locales.Single(l => l.Name == "us");
+                var id1 = new Identity(locale1);
+                var acct1 = new Account("a0") { AccountName = "n0", IdentityTokens = id1 };
+                p.Accounts.Add(acct1);
+
+                // update just-added item. note: this is different than the subscription which happens on initial collection load. ensure this works also
+                acct1.AccountName = "new";
+            }
+
+            // verify save property
+            using (var p = new AccountsPersister(TestFile))
+            {
+                var acct0 = p.Accounts.AccountsSettings[0];
+                acct0.AccountName.Should().Be("new");
+            }
+        }
+
         // update Account property. must be non-destructive to all other data
         [TestMethod]
         public void update_Account_field()
@@ -317,13 +344,13 @@ namespace AccountsTests
                 var locale1 = Localization.Locales.Single(l => l.Name == "us");
                 var id1 = new Identity(locale1);
                 var acct1 = new Account("a0") { AccountName = "n0", IdentityTokens = id1 };
-                p.Accounts.UNITTEST_Seed(acct1);
+                p.Accounts.Add(acct1);
 
                 var locale2 = Localization.Locales.Single(l => l.Name == "uk");
                 var id2 = new Identity(locale2);
                 var acct2 = new Account("a1") { AccountName = "n1", IdentityTokens = id2 };
 
-                p.Accounts.UNITTEST_Seed(acct2);
+                p.Accounts.Add(acct2);
             }
 
             // update AccountName on existing file
@@ -363,13 +390,13 @@ namespace AccountsTests
                 var locale1 = Localization.Locales.Single(l => l.Name == "us");
                 var id1 = new Identity(locale1);
                 var acct1 = new Account("a0") { AccountName = "n0", IdentityTokens = id1 };
-                p.Accounts.UNITTEST_Seed(acct1);
+                p.Accounts.Add(acct1);
 
                 var locale2 = Localization.Locales.Single(l => l.Name == "uk");
                 var id2 = new Identity(locale2);
                 var acct2 = new Account("a1") { AccountName = "n1", IdentityTokens = id2 };
 
-                p.Accounts.UNITTEST_Seed(acct2);
+                p.Accounts.Add(acct2);
             }
 
             // update identity on existing file
@@ -413,13 +440,13 @@ namespace AccountsTests
                 var locale1 = Localization.Locales.Single(l => l.Name == "us");
                 var id1 = new Identity(locale1);
                 var acct1 = new Account("a0") { AccountName = "n0", IdentityTokens = id1 };
-                p.Accounts.UNITTEST_Seed(acct1);
+                p.Accounts.Add(acct1);
 
                 var locale2 = Localization.Locales.Single(l => l.Name == "uk");
                 var id2 = new Identity(locale2);
                 var acct2 = new Account("a1") { AccountName = "n1", IdentityTokens = id2 };
 
-                p.Accounts.UNITTEST_Seed(acct2);
+                p.Accounts.Add(acct2);
             }
 
             // update identity on existing file
@@ -448,4 +475,154 @@ namespace AccountsTests
             }
         }
     }
+
+    [TestClass]
+    public class retrieve : AccountsTestBase
+    {
+        [TestMethod]
+        public void get_where()
+        {
+            var us = Localization.Locales.Single(l => l.Name == "us");
+            var idUs = new Identity(us);
+            var acct1 = new Account("cng") { IdentityTokens = idUs, AccountName = "foo" };
+
+            var uk = Localization.Locales.Single(l => l.Name == "uk");
+            var idUk = new Identity(uk);
+            var acct2 = new Account("cng") { IdentityTokens = idUk, AccountName = "bar" };
+
+            var accounts = new Accounts();
+            accounts.Add(acct1);
+            accounts.Add(acct2);
+
+            accounts.GetAccount("cng", "uk").AccountName.Should().Be("bar");
+        }
+    }
+
+    [TestClass]
+    public class upsert : AccountsTestBase
+    {
+        [TestMethod]
+        public void upsert_new()
+        {
+            var accounts = new Accounts();
+            accounts.AccountsSettings.Count.Should().Be(0);
+
+            accounts.Upsert("cng", "us");
+
+            accounts.AccountsSettings.Count.Should().Be(1);
+            accounts.GetAccount("cng", "us").AccountId.Should().Be("cng");
+        }
+
+        [TestMethod]
+        public void upsert_exists()
+        {
+            var accounts = new Accounts();
+            var orig = accounts.Upsert("cng", "us");
+            orig.AccountName = "foo";
+
+            var exists = accounts.Upsert("cng", "us");
+            exists.AccountName.Should().Be("foo");
+
+            orig.Should().IsSameOrEqualTo(exists);
+        }
+    }
+
+    [TestClass]
+    public class delete : AccountsTestBase
+    {
+        [TestMethod]
+        public void delete_account()
+        {
+            var accounts = new Accounts();
+            var acct = accounts.Upsert("cng", "us");
+            accounts.AccountsSettings.Count.Should().Be(1);
+
+            var removed = accounts.Delete(acct);
+            removed.Should().BeTrue();
+
+            accounts.AccountsSettings.Count.Should().Be(0);
+        }
+
+        [TestMethod]
+        public void delete_where()
+        {
+            var accounts = new Accounts();
+            var acct = accounts.Upsert("cng", "us");
+            accounts.AccountsSettings.Count.Should().Be(1);
+
+            accounts.Delete("baz", "baz").Should().BeFalse();
+            accounts.AccountsSettings.Count.Should().Be(1);
+
+            accounts.Delete("cng", "us").Should().BeTrue();
+            accounts.AccountsSettings.Count.Should().Be(0);
+        }
+
+        [TestMethod]
+        public void deleted_account_should_not_persist_file()
+        {
+            Account acct;
+
+            using (var p = new AccountsPersister(new Accounts(), TestFile))
+            {
+                acct = p.Accounts.Upsert("foo", "us");
+                p.Accounts.AccountsSettings.Count.Should().Be(1);
+                acct.AccountName = "old";
+            }
+
+            using (var p = new AccountsPersister(new Accounts(), TestFile))
+            {
+                p.Accounts.Delete(acct);
+                p.Accounts.AccountsSettings.Count.Should().Be(0);
+            }
+
+            using (var p = new AccountsPersister(new Accounts(), TestFile))
+            {
+                File.ReadAllText(TestFile).Should().Be("{\r\n  \"AccountsSettings\": []\r\n}".Trim());
+
+                acct.AccountName = "new";
+
+                File.ReadAllText(TestFile).Should().Be("{\r\n  \"AccountsSettings\": []\r\n}".Trim());
+            }
+        }
+    }
+
+    // account.Id + Locale.Name -- must be unique
+    [TestClass]
+    public class validate : AccountsTestBase
+    {
+        [TestMethod]
+        public void violate_validation()
+        {
+            var accounts = new Accounts();
+
+            var localeIn = Localization.Locales.Single(l => l.Name == "us");
+            var idIn = new Identity(localeIn);
+
+            var a1 = new Account("a") { AccountName = "one", IdentityTokens = idIn };
+            accounts.Add(a1);
+
+            var a2 = new Account("a") { AccountName = "two", IdentityTokens = idIn };
+
+            // violation: validate()
+            Assert.ThrowsException<InvalidOperationException>(() => accounts.Add(a2));
+        }
+
+        [TestMethod]
+        public void identity_violate_validation()
+        {
+            var accounts = new Accounts();
+
+            var localeIn = Localization.Locales.Single(l => l.Name == "us");
+            var idIn = new Identity(localeIn);
+
+            var a1 = new Account("a") { AccountName = "one", IdentityTokens = idIn };
+            accounts.Add(a1);
+
+            var a2 = new Account("a") { AccountName = "two" };
+            accounts.Add(a2);
+
+            // violation: GetAccount.SingleOrDefault
+            Assert.ThrowsException<InvalidOperationException>(() => a2.IdentityTokens = idIn);
+        }
+    }
 }