Patient/client identification

I am new to this specialty and am wondering how other organizations address the issue of patient/client identification. This organization includes a specialty hospital (rehab), numerous group homes, a school, and a health center from which meds for those attending school and those living in the group homes are administered. From a safety perspective, how do you ensure that the person you are medicating is indeed the person for whom the medications are intended? What do you use as your 2 identifiers?
I'm certain I'll have many more questions. Thanks in advance for your assistance.