Yes, you could go to the GUI but the T-SQL can be quicker.

use <<database>>

SELECT p. NAME
,m. NAME
FROM sys .database_role_members rm
JOIN sys .database_principals p
ON rm. role_principal_id = p .principal_id
JOIN sys .database_principals m
ON rm. member_principal_id = m .principal_id

 

This will return all the principles associated to the database in question against what role they have.