diff --git a/callofduty/auth.py b/callofduty/auth.py
index eb58caa..ce0a8ec 100644
--- a/callofduty/auth.py
+++ b/callofduty/auth.py
@@ -6,7 +6,7 @@
 
 from .client import Client
 from .errors import LoginFailure
-from .http import HTTP
+from .http import HTTP, JSONorText
 
 log: logging.Logger = logging.getLogger(__name__)
 
@@ -17,10 +17,12 @@ class Auth:
 
     Parameters
     ----------
-    email : str
+    email : str, optional
         Activision account email address.
-    password : str
+    password : str, optional
         Activision account password.
+    sso : str, optional
+        Activision single sign-on cookie value.
     """
 
     loginUrl: str = "https://profile.callofduty.com/cod/mapp/login"
@@ -29,12 +31,21 @@ class Auth:
     _accessToken: Optional[str] = None
     _deviceId: Optional[str] = None
 
-    def __init__(self, email: str, password: str):
-        self.email: str = email
-        self.password: str = password
-        
+    def __init__(
+        self,
+        email: Optional[str] = None,
+        password: Optional[str] = None,
+        sso: Optional[str] = None,
+    ):
+        self.email: Optional[str] = email
+        self.password: Optional[str] = password
+        self.sso: Optional[str] = sso
+
         self.session: httpx.AsyncClient = httpx.AsyncClient()
 
+        if self.sso is not None:
+            self.session.cookies.set("ACT_SSO_COOKIE", self.sso)
+
     @property
     def AccessToken(self) -> Optional[str]:
         """
@@ -107,19 +118,32 @@ async def SubmitLogin(self):
 
             if res.status_code != 200:
                 raise LoginFailure(f"Failed to login (HTTP {res.status_code})")
-
-
-async def Login(email: str, password: str) -> Client:
+            elif isinstance(data := await JSONorText(res), dict):
+                if data.get("success") is not True:
+                    # The API tends to return HTTP 200 even when an error occurs
+                    raise LoginFailure(
+                        f"Failed to login (HTTP {res.status_code}), "
+                        + data.get("token", data)
+                    )
+
+
+async def Login(
+    email: Optional[str] = None,
+    password: Optional[str] = None,
+    sso: Optional[str] = None,
+) -> Client:
     """
     Convenience function to make login with the Call of Duty authorization flow
-    as easy as possible.
+    as easy as possible. Requires one of email and password or sso cookie value.
 
     Parameters
     ----------
-    email : str
+    email : str, optional
         Activision account email address.
-    password : str
+    password : str, optional
         Activision account password.
+    sso: str, optional
+        Activision single sign-on cookie value.
 
     Returns
     -------
@@ -127,9 +151,16 @@ async def Login(email: str, password: str) -> Client:
         Authenticated Call of Duty client.
     """
 
-    auth: Auth = Auth(email, password)
+    auth: Auth = Auth(email, password, sso)
+
+    if (email is None) and (sso is None):
+        raise LoginFailure("Failed to login, insufficient credentials provided")
+    elif (email is not None) and (password is not None):
+        await auth.RegisterDevice()
+        await auth.SubmitLogin()
 
-    await auth.RegisterDevice()
-    await auth.SubmitLogin()
+        return Client(HTTP(auth))
+    elif sso is not None:
+        await auth.RegisterDevice()
 
-    return Client(HTTP(auth))
+        return Client(HTTP(auth))
diff --git a/test.py b/test.py
index 8921959..0477712 100644
--- a/test.py
+++ b/test.py
@@ -9,9 +9,12 @@
 
 async def main():
     load_dotenv()
-    client = await callofduty.Login(
-        os.environ["ATVI_EMAIL"], os.environ["ATVI_PASSWORD"]
-    )
+
+    # client = await callofduty.Login(
+    #     os.environ["ATVI_EMAIL"], os.environ["ATVI_PASSWORD"]
+    # )
+    # OR
+    # client = await callofduty.Login(sso=os.environ["ATVI_SSO"])
 
     # season = await client.GetLootSeason(Title.BlackOps4, 3)
     # print(f"{season.title.name}: {season.name}")
@@ -43,10 +46,10 @@ async def main():
     # for account in accounts:
     #     print(f"{account.username} ({account.platform.name})")
 
-    # player = await client.GetPlayer(Platform.BattleNet, "Mxtive#1930")
+    # player = await client.GetPlayer(Platform.BattleNet, "Yeah#11207")
     # print(f"{player.username} ({player.platform.name})")
 
-    # player = await client.GetPlayer(Platform.BattleNet, "Mxtive#1930")
+    # player = await client.GetPlayer(Platform.BattleNet, "Yeah#11207")
     # summary = await player.matchesSummary(Title.ModernWarfare, Mode.Warzone, limit=20)
     # print(summary)
 
@@ -65,13 +68,13 @@ async def main():
     #     print(f"#{entry.rank}: {entry.username} ({entry.platform.name})")
 
     # leaderboard = await client.GetPlayerLeaderboard(
-    #     Title.BlackOps4, Platform.BattleNet, "Mxtive#1930"
+    #     Title.BlackOps4, Platform.BattleNet, "Yeah#11207"
     # )
     # for entry in leaderboard.entries:
-    #     if entry.username == "Mxtive#1930":
+    #     if entry.username == "Yeah#11207":
     #         print(f"#{entry.rank}: {entry.username} ({entry.platform.name})")
 
-    # player = await client.GetPlayer(Platform.Steam, "RdJokr")
+    # player = await client.GetPlayer(Platform.Steam, "Mxtive")
     # leaderboard = await player.leaderboard(Title.WWII)
     # for entry in leaderboard.entries:
     #     if entry.username == player.username:
@@ -112,11 +115,11 @@ async def main():
     #     for mode in maps[mapName]:
     #         print(f" - {mode}")
 
-    # match = (await client.GetPlayerMatches(Platform.Activision, "Yeah#8649242", Title.ModernWarfare, Mode.Warzone, limit=3))[0]
+    # match = (await client.GetPlayerMatches(Platform.BattleNet, "Yeah#11207", Title.ModernWarfare, Mode.Warzone, limit=3))[0]
     # teams = await match.teams()
     # print(teams)
 
-    # player = await client.GetPlayer(Platform.BattleNet, "Mxtive#1930")
+    # player = await client.GetPlayer(Platform.BattleNet, "Yeah#11207")
     # match = (await player.matches(Title.ModernWarfare, Mode.Multiplayer, limit=3))[1]
     # match = await client.GetMatch(Title.ModernWarfare, Platform.Activision, match.id)
     # teams = await match.teams()
@@ -126,7 +129,7 @@ async def main():
     # details = await match.details()
     # print(details)
 
-    # player = await client.GetPlayer(Platform.BattleNet, "Mxtive#1930")
+    # player = await client.GetPlayer(Platform.BattleNet, "Yeah#11207")
     # match = (await player.matches(Title.ModernWarfare, Mode.Multiplayer, limit=3))[1]
     # match = await client.GetFullMatch(Platform.Activision, Title.ModernWarfare, Mode.Multiplayer, match.id)
     # print(match)
@@ -135,7 +138,7 @@ async def main():
     # for player in results:
     #     print(f"{player.username} ({player.platform.name})")
 
-    # player = await client.GetPlayer(Platform.BattleNet, "Mxtive#1930")
+    # player = await client.GetPlayer(Platform.BattleNet, "Yeah#11207")
     # profile = await player.profile(Title.ModernWarfare, Mode.Multiplayer)
     # print(profile)
 
@@ -233,7 +236,7 @@ async def main():
     #     if member.username != squad.owner.username:
     #         print(f"Member: {member.username} ({member.platform.name})")
 
-    # squad = await client.GetPlayerSquad(Platform.Activision, "Yeah#8649242")
+    # squad = await client.GetPlayerSquad(Platform.Activision, "Yeah#11207")
     # print(f"{squad.name} - {squad.description}")
     # print(f"Owner: {squad.owner.username} ({squad.owner.platform.name})")
     # for member in squad.members: