The study used data collected from electronic adherence monitors, questionnaires, and computerized medical records that contained blood pressure readings during a prior investigation of antihypertensive adherence. This earlier investigation, conducted from 1994 to 1997, involved 286 members of Harvard Pilgrim Health Care who were on single drug therapy for mild to moderate hypertension. Objective 1 evaluated the impact of temporal factors such as weekend versus weekday, holidays, seasons, and impending medical appointments on adherence by analyzing their effects on the daily rate of dosing recorded by electronic medication monitors. Time trend models were used for this purpose. Objective 2 assessed the impact of pharmacologic duration of action on the level of antihypertensive adherence required to maintain a goal blood pressure of <140/90 mmHg. This involved determining if the relationship between adherence and blood pressure was modified by the duration of drug effect. Objective 3 concerning correlates of accuracy of reported adherence was approached by verifying reported adherence against electronically measured adherence. Predictors and correlates of accurately reported adherence such as patient age, gender, race/ethnicity, education, socioeconomic status, health beliefs, and measures of health status were then identified by cross tabulating and statistical modeling accurate reporting against these factors.