The purpose of the naltrexone trial is to evaluate whether AGATE effectively measures and enhances medication adherence in the context of naltrexone treatment for problem drinking. Participants will be heavy/problem drinkers, recruited from the greater Albuquerque area, who are interested in either reducing or stopping their drinking and deemed to be candidates for naltrexone pharmacotherapy by the study psychiatrist, Dr. Arenella. All participants will be prescribed naltrexone, 50 mg, once daily, for eight weeks, and receive smartphones. Participants will be randomly assigned to receive either AGATE or SASED, a web-based alcohol and side-effects diary via smartphone. The primary outcome will be percent of scheduled doses that were taken during the eight week trial, as measured by the Medication Event Monitoring System (MEMS, Aardex Group, Union City, CA), pill counts, and using the timeline follow-back (TLFB) method.