The objective of this study is to determine whether providing Medicare beneficiaries with a web-based patient-centered decision tool to help them choose among prescription medication coverage plans improves outcomes for patients including a greater likelihood of changing a plan, better coverage for prescribed drugs, less decisional conflict when choosing plans, and greater satisfaction with the choice process relative to current practice. In this study, the investigators tested the effectiveness of two versions of a web-based tool (called CHOICE) to help people choose among Medicare Part D plans (Treatments A and B) relative to standard care (Control). Both treatment arms incorporated simplified design and automated importation of an individual's prescription drugs relative to standard care. The treatment arms varied based on whether they provided expert guidance on recommended plans. In the control arm, study participants were directed to the existing, publicly available Medicare.gov website and received instructions on how to download their drugs from the Palo Alto Medical Foundation (PAMF) patient-facing online personal health portal (myhealthonline). The study sample included PAMF patients who were enrolled in Part D plans (not Medicare Advantage) during the 2016 enrollment period. Prior to the 2017 open enrollment period (October 15 to December 7, 2016), we invited a subset of PAMF patients not covered by either MediCal or a Medicare Advantage plan, aged 66-85, residing in 4 counties served by PAMF, and with at least one active medication order to participate in a study examining the effectiveness of decision tools that provide personalized information on the financial implications of enrolling in different Part D plans. The primary study outcomes included 1) Plan switching, 2) Decisional conflict 3) Satisfaction with the choice process, and 4) Change in generosity of coverage of prescription drugs. The investigators measured the primary study outcomes using a combination of administrative data and a post open enrollment survey. The investigators also collected information on individual characteristics at the time of enrollment in the study and implemented a survey examining use of the intervention tool to assess patient experience at the time of use.