The equivalent is a BIT field.
In SQL you use 0 and 1 to set a bit field (just as a yes/no field in Access). In Management Studio it displays as a false/true value (at least in recent versions).
When accessing the database through ASP.NET it will expose the field as a boolean value.
The BIT datatype is generally used to store boolean values (0 for false, 1 for true).