In order to join, you must receive an invitation from the Phi Theta Kappa chapter at your college. The local chapter determines eligibility, and each chapter has varying requirements for membership. You will need to contact the local PTK chapter advisor to determine if you are eligible.
If you are unsure whom to contact, you can locate the Phi Theta Kappa advisor on your campus by using the Advisor Search.*If you have already been invited and received your passcode, you can accept membership here: http://www.ptk.org/joinus.