The primary study endpoints are taking and timing adherence as assessed by electronic monitoring. There are numerous methods of assessing adherence to medication. They each have their strengths and weaknesses, and some are only feasible in the research but not clinical setting. The most commonly used methods of assessing adherence are (1) provider assessment, (2) structured self-report (3) pharmacy refill data (4) electronic monitoring (5) pill counts and (6) directly observed therapy. Electronic monitoring technology has been widely used in research studies of HIV medication adherence and is regarded by many as the most accurate method of assessing medication adherence (Weiss et al. 2009). In this method, the medication bottle cap has a microchip which records all openings and closings of the bottle. This microchip provides the researcher with a precise record of the date and time of each bottle opening. This method has been shown to be closely associated with random home pill count (Bangsberg et al., 2001a), viral suppression (Bangsberg et al., 2000; Paterson et al., 2000; Arnsten et al., 2001; Walsh et al., 2002b; Moss et al., 2004), and drug resistance (Walsh et al., 2002b). Studies have consistently found that provider assessment of adherence is poor (Bangsberg et al., 2001b; Gross et al., 2002; and Miller et al., 2002). Self-reported adherence tends to provide an over-estimate of actual adherence (Weiss et al. 2009). Pharmacy refill data is best employed when patients use one pharmacy for all prescriptions, pharmacy data are easily accessible to the clinician by computer, and prescriptions are not automatically delivered without the patient needing to request them or pick them up. Patients in clinical research studies are often asked to bring their medication to study visits so that the change in the number of pills (accounting for refills) since the last visit can be used to assess adherence. Potential problems associated with these announced pill counts are that patients may forget to bring their medication to study visits, and nonadherent patients may throw out pills prior to the visit ("pill dumps") to avoid being labeled nonadherent. While directly observed therapy (DOT) provides a highly accurate assessment of adherence, the cost and intrusiveness of observing all doses of medication ingestion make it an impractical method of ARV adherence assessment, except in very specific settings (e.g., prisons or nursing homes).