Randomized, double-blind, two-group design. Within each of the groups, half of the subjects were on lovastatin and half on placebo. The main outcome measure was medication intake monitored daily and unobtrusively with the MEMS electronic monitor. For each subject, event time series of six months duration were obtained. The effect of these interventions were determined on average adherence at two and six months; and variability of adherence. In addition, the relative cost effectiveness of each intervention was examined by a recalculation of sample size needs based upon increased adherence and related cholesterol lowering. Ancillary goals of the study included: determining the components of variability of medication intake using statistical modeling techniques; and covariates of treatment effects, including baseline daily hassles, problem solving skills, and generalized expectancy for success.