diff --git a/dnd_item/cli.py b/dnd_item/cli.py
index 21f8733..85f4590 100644
--- a/dnd_item/cli.py
+++ b/dnd_item/cli.py
@@ -16,7 +16,9 @@ app_state = {}
 
 
 @app.callback()
-def main():
+def main(
+    cr: int = typer.Option(default=None, help='The Challenge Rating to use when determining rarity.'),
+):
     debug = os.getenv("FANITEM_DEBUG", None)
     logging.basicConfig(
         format="%(name)s %(message)s",
@@ -25,20 +27,21 @@ def main():
     )
     logging.getLogger('markdown_it').setLevel(logging.ERROR)
 
+    app_state['cr'] = cr or 0
     app_state['data'] = Path(__file__).parent / Path("sources")
 
 
 @app.command()
 def weapon(count: int = typer.Option(1, help="The number of weapons to generate.")):
     console = Console()
-    for weapon in WeaponGenerator().random(count):
+    for weapon in WeaponGenerator().random(count=count, challenge_rating=app_state['cr']):
         console.print(weapon.details)
 
 
 @app.command()
 def magic_weapon(count: int = typer.Option(1, help="The number of weapons to generate.")):
     console = Console()
-    for weapon in MagicWeaponGenerator().random(count):
+    for weapon in MagicWeaponGenerator().random(count=count, challenge_rating=app_state['cr']):
         console.print(weapon.details)
 
 
diff --git a/dnd_item/sources/magic_damage_types.yaml b/dnd_item/sources/magic_damage_types.yaml
index c03b63d..bc04cc1 100644
--- a/dnd_item/sources/magic_damage_types.yaml
+++ b/dnd_item/sources/magic_damage_types.yaml
@@ -5,7 +5,6 @@ metadata:
     - adjective
   frequencies:
     default:
-      magic: 1.0
       fire: 1.0
       cold: 1.0
       acid: 1.0
@@ -16,9 +15,6 @@ metadata:
       force: 1.0
       necrotic: 1.0
       radiant: 1.0
-magic:
-  - magic
-  - magical
 fire:
   - flames, fire
   - flaming, burning
diff --git a/dnd_item/sources/rarity.yaml b/dnd_item/sources/rarity.yaml
index 6a04f39..24165a8 100644
--- a/dnd_item/sources/rarity.yaml
+++ b/dnd_item/sources/rarity.yaml
@@ -1,15 +1,46 @@
+# 5e Iteam Rarity Distributions By Challenge Rating
+#
+# This distribution is based on this excellent analysis of the DMG loot tables, though 
+# I have smoothed and tweaked a little bit (the CR17+ frequencies are brokekn IMO):
+#
+# https://www.enworld.org/threads/analysis-of-typical-magic-item-distribution.395770/
+# 
 metadata:
   headers:
-    - Rarity
+    - rarity
   frequencies:
-    default:
-      Common: 1.0
-      Uncommon: 0.8
-      Rare: 0.5
-      Legendary: 0.1
-      Unique: 0.05
-Common:
-Uncommon:
-Rare:
-Legendary:
-Unique:
+    'default':
+      common: 1.0
+      uncommon: 1.0
+      rare: 1.0
+      very rare: 1.0
+      legendary: 1.0
+    '1-4':
+      common: 0.75
+      uncommon: 0.5
+      rare: 0.25
+      very rare: 0.0
+      legendary: 0.0
+    '5-10':
+      common: 0.5
+      uncommon: 0.75
+      rare: 0.25
+      very rare: 0.05
+      legendary: 0.0
+    '11-16':
+      common: 0.25
+      uncommon: 0.5
+      rare: 0.75
+      very rare: 0.5
+      legendary: 0.1
+    '17':
+      common: 0.05
+      uncommon: 0.05
+      rare: 0.5
+      very rare: 0.5
+      legendary: 0.3
+common:
+uncommon:
+rare:
+very rare:
+legendary:
diff --git a/dnd_item/types.py b/dnd_item/types.py
index 6f82184..7962db7 100644
--- a/dnd_item/types.py
+++ b/dnd_item/types.py
@@ -12,7 +12,7 @@ from random_sets.sets import WeightedSet, DataSourceSet
 sources = Path(__file__).parent / Path("sources")
 MAGIC_DAMAGE = DataSourceSet(sources / Path('magic_damage_types.yaml'))
 WEAPON_TYPES = DataSourceSet(sources / Path('weapons.yaml'))
-#  RARITY = DataSourceSet(sources / Path('rarity.yaml'))
+RARITY = DataSourceSet(sources / Path('rarity.yaml'))
 
 
 @dataclass
@@ -143,9 +143,11 @@ class ItemGenerator:
         self,
         templates: WeightedSet,
         types: WeightedSet,
+        rarity: WeightedSet = RARITY,
     ):
         self.types = types
         self.templates = templates
+        self.rarity = rarity
 
     def random_properties(self) -> dict:
         """
@@ -167,14 +169,30 @@ class ItemGenerator:
         properties = {
             'template':  self.templates.random(),
             'type':  self.types.random(),
+            'rarity': self.rarity.random(),
         }
         return properties
 
-    def random(self, count: int = 1) -> list:
+    def random(self, count: int = 1, challenge_rating: int = 0) -> list:
         """
         Generate one or more random Item instances by selecting random values
         from the available types and template
         """
+
+        # select the appropriate frequency distributionnb ased on the specified
+        # challenge rating. By default, all rarities are weighted equally.
+        if challenge_rating in range(1, 5):
+            frequency = '1-4'
+        elif challenge_rating in range(5, 11):
+            frequency = '5-10'
+        elif challenge_rating in range(11, 17):
+            frequency = '11-16'
+        elif challenge_rating >= 17:
+            frequency = '17'
+        else:
+            frequency = 'default'
+        self.rarity.set_frequency(frequency)
+
         items = []
         for _ in range(count):
             items.append(self.item_class.from_dict(**self.random_properties()))
@@ -192,10 +210,11 @@ class WeaponGenerator(ItemGenerator):
         self,
         templates: WeightedSet = None,
         types: WeightedSet = WEAPON_TYPES,
+        rarity: WeightedSet = RARITY,
     ):
         if not templates:
             templates = WeightedSet(('{type.name}', 1.0),)
-        super().__init__(types=types, templates=templates)
+        super().__init__(types=types, templates=templates, rarity=rarity)
 
 
 class MagicWeaponGenerator(WeaponGenerator):
@@ -206,6 +225,7 @@ class MagicWeaponGenerator(WeaponGenerator):
         self,
         templates: WeightedSet = None,
         types: WeightedSet = WEAPON_TYPES,
+        rarity: WeightedSet = RARITY,
         magic: WeightedSet = MAGIC_DAMAGE,
     ):
         self.magic = magic
@@ -216,7 +236,7 @@ class MagicWeaponGenerator(WeaponGenerator):
                 # "Burning Lance"
                 ('{magic.adjective} {type.name}', 1.0),
             )
-        super().__init__(types=types, templates=templates)
+        super().__init__(types=types, templates=templates, rarity=rarity)
 
     def random_properties(self):
         """