This study has a number of limitations. First, generalizability is compromised by the use of a small number of sites. However, the ethnic, socioeconomic, and health care financing mix was far broader than in previous CC studies that focused on middle class, working, white patients in health maintenance organizations, and the absence of site and racial differences suggests that beneficial effects were generalized to the entire group. Second, all subjects were provided medication free of charge, which differs from the "real world" of primary care. Third, the use of anxiety disorder specialists and university sites (in 2 of the 3 settings) may suggest it would be difficult to implement this intervention in certain rural and urban inner-city settings owing to a lack of specialists. However, this simple intervention might be carried out by well-trained physician extenders (such as nurses) with psychiatric supervision, as is being done for depression in the Kaiser Health System (Oakland, Calif).46 Fourth, it is not possible to determine which components of the intervention were responsible for the beneficial effects since no systematic assessment of the treatment process was made. Nonetheless, it seems that the provision of skilled assessment and treatment explanations, the scheduling of regular patient-clinician contact, and the ongoing monitoring of treatment tolerance, adherence, and outcomes were most important in possibly allowing better management of medication adverse effects and dose adjustments. Finally, this effectiveness study, by nature, lacked certain methodologic controls common to more internally valid efficacy studies. The PDSS has not been validated for use via the telephone or by lay interviewers, and the ASI has been infrequently used as a pharmacotherapeutic outcome measure,35 though its content is unusually well suited for primary care PD. Efficacy studies have established that 40 mg of paroxetine is the efficacious dose,43 while our modal paroxetine dose was 20 mg, the most common dose in primary care clinics47 (Risa B. Weisberg, PhD, Martin Keller, MD, e-mail communication, March 2001) and an effective dose for some patients.43 Although our protocol allowed psychiatrists to stop at 20 mg, it is possible that pushing the dose higher could have increased response in CC patients.