Many post Acute Coronary Syndrome(ACS) patients do not take their medications (including aspirin) as prescribed, leading to an increase in mortality. Patients enrolled in this study will be enrolled into one of two groups. Patients in the first group will have their medication adherence measured, but will receive all other care as usual. Patients in the second group will also have their medication adherence measured, but they will receive telephone-delivered problem solving therapy (PST) in addition to their usual care. The two groups will be combined to determine the Minimally Effective Dose (MED) and the Maximally Tolerated Dose (MTD) for adherence to aspirin. The medication adherence of the PST group will improve by 20% (<55% to >75%).