Recent epidemiological data has indicated an increasing trend in the non-medical use of prescription drugs (NMUPD) among college students. NMUPD involves using a prescription medication without a prescription, or using the medication in a manner inconsistent with a health care provider's instructions. Among college students, prescription stimulants having the highest ratio of non-medical to medical use and the highest rate of illicit selling and trading on college campuses. The increased prevalence is accompanied by increased risk, as 18-25 year olds have had the highest rate of emergency department visits for non-medical use of prescription stimulants (NMUPS). The current study examined the prevalence of self-reported NMUPS among college students and the impact of social norms on NMUPS. Social norm theory has accounted for other health related behaviors (e.g., alcohol and marijuana use) and has been utilized in brief interventions targeting risky health behaviors. To date, no studies have examined the impact of social norms on NMUPS. The current study included 959 participants who completed an on-line survey that assessed for NMUPS, self-approval for NMUPS, and perceived descriptive and injunctive norms for NMUPS. Similar to previous research on alcohol and marijuana use, students overestimated the prevalence of NMUPS and this overestimation was related to past year NMUPS. Perceived close friend and parental approval of NMUPS was positively related to self-approval and past-year NMUPS. Overall, the study broadens the existing literature on NMUPS and provides a platform for developing brief interventions that target this risky behavior. [The dissertation citations contained here are published with the permission of ProQuest LLC. Further reproduction is prohibited without permission. Copies of dissertations may be obtained by Telephone (800) 1-800-521-0600. Web page: http://www.proquest.com.bibliotheek.ehb.be/en-US/products/dissertations/individuals.shtml.]