Sober Truth on Preventing Underage Drinking Reauthorization Act or the STOP Act - Amends the Public Health Service Act to reauthorize the program to reduce underage drinking for FY2012-FY2016. Makes revisions to such program, including by: (1) revising reporting requirements on state programs on underage drinking; (2) expanding the national media campaign to prevent underage drinking; (3) requiring the Administrator of the Substance Abuse and Mental Health Services Administration to make grants to professional pediatric provider organizations to increase effective practices, including the screening of children and adolescents for alcohol use, to reduce the prevalence of alcohol use among individuals under the age of 21, including college students; and (4) expanding state public health surveillance of alcohol use and alcohol-related conditions among individuals between the ages of 18 and 20.