* Your institution: Each college and university sets its own policies. Some may have a minimum number of credits you can register for (e.g., 3 credits), while others might allow you to take just 1 credit hour.
* Your program: Your academic program might have specific requirements or recommendations regarding summer coursework. This is especially true if you are on a strict timeline to graduate.
To find the minimum credit hours allowed for summer classes, you must check your college or university's registrar's office website or student handbook.