Background: Humana currently sends messages to members as a reminder to remain adherent with their medication. Since some members may view insurance companies skeptically, we wanted to see if similar messaging reminders from trusted third parties would be more effective than messaging that came from their health insurance plans. The third parties included a celebrity (Florence Henderson), a pharmacist, and the member’s primary care physician (PCP). Objective: The primary purpose of this research was to test the relative impact of medication adherence messages emanating from different sources. Methods: In this prospective, randomized control study, 17,771 members were randomized to five treatment arms and two control arms. The study sample was comprised of MAPD members who had a baseline PDC between .60 and .85 in at least one of the following medication groups: hypertension, diabetes, and hyperlipidemia. Each study member received two communications from their trusted third party: a postcard and a pre-recorded phone call. Generally, the postcard and phone call would be from the same source; in one “combination” treatment arm, the postcard came from the pharmacist and the phone call came from the celebrity. The postcards were mailed in November 2014 and the pre-recorded calls were completed in December 2014. The main outcomes of interest were changes in PDC scores between November 2014 and May 2015. Results: Overall, the pharmacist-celebrity combination, pharmacist- only, and PCP treatments yielded the best results. The Pharmacist-celebrity treatment increased PDC scores by .037, the Pharmacist-only treatment increased PDC scores by .042, and the PCP treatment increased PDC scores by .033 over control (all significant at p=.05). All messages increased PDC scores for women, however only the pharmacist-celebrity treatment was statistically significant, with a PDC increase of .043 (p=.05). For men, the pharmacist-only, PCP, and pharmacist-celebrity treatments increased PDC scores by .079, .071, and .029, respectively, at p=.05. For the patients on hypertension medications, the pharmacist-only, PCP, and pharmacist-celebrity treatments increased PDC scores by .045, .043, and .041, respectively, at p=.05. Conclusion: There were statistically-significant improvements in adherence to hypertension medications for the pharmacist-only, PCP, and pharmacist-celebrity treatment arms. Men and women responded to third parties differently. Based on the results, we would like further test messages delivered from third parties to understand when and how sources induce different responses.