diff --git a/conservancy_beancount/data.py b/conservancy_beancount/data.py
index 829cec7..b102f3b 100644
--- a/conservancy_beancount/data.py
+++ b/conservancy_beancount/data.py
@@ -220,16 +220,19 @@ class Account(str):
                 yield account
 
     @classmethod
-    def iter_accounts(cls, s: str) -> Iterator['Account']:
+    def iter_accounts(cls, s: Optional[str]=None) -> Iterator['Account']:
         """Iterate account objects by name or classification
 
+        With no argument, returns an iterator of all known account names.
         If you pass in a root account name, or a valid account string, returns
         an iterator of all accounts under that account in the hierarchy.
         Otherwise, returns an iterator of all accounts with the given
         ``classification`` metadata.
         """
+        if s is None:
+            return (cls(acct) for acct in cls._meta_map)
         # We append a stub subaccount to match root accounts.
-        if cls.is_account(f'{s}:Test'):
+        elif cls.is_account(f'{s}:RootsOK'):
             return cls.iter_accounts_by_hierarchy(s)
         else:
             return cls.iter_accounts_by_classification(s)
diff --git a/tests/test_data_account.py b/tests/test_data_account.py
index 9546d32..106d114 100644
--- a/tests/test_data_account.py
+++ b/tests/test_data_account.py
@@ -444,6 +444,8 @@ def test_iter_accounts_by_classification(asset_hierarchy, arg, expect_subaccts):
     }
 
 @pytest.mark.parametrize('arg,expect_subaccts', [
+    (None, ['Bank:CD', 'Bank:Checking', 'Bank:Savings', 'Cash',
+            'Investment:Commodities', 'Investment:Stocks']),
     ('Assets', ['Bank:CD', 'Bank:Checking', 'Bank:Savings', 'Cash',
                 'Investment:Commodities', 'Investment:Stocks']),
     ('Assets:Bank', ['CD', 'Checking', 'Savings']),
@@ -454,7 +456,7 @@ def test_iter_accounts_by_classification(asset_hierarchy, arg, expect_subaccts):
     ('Unused classification', []),
 ])
 def test_iter_accounts(asset_hierarchy, arg, expect_subaccts):
-    if arg.startswith('Assets'):
+    if arg and arg.startswith('Assets'):
         prefix = arg
     else:
         prefix = 'Assets'