The present study was undertaken to examine the utility of the Center for Epidemiological Studies-Depression (CES-D) scale and the Beck Depression Inventory (BDI) as screening instruments for primary care clinic patients. We examined: 1) patients' willingness to complete the scales; 2) the level of agreement between the screening instruments and DSM-III diagnosis of Major Depressive Episode, based on the NIMH Diagnostic Interview Schedule (DIS); 3) the effect on detection rates of raising the cut-off score for each depression screen; and 4) the factor structure of the CES-D in our primary care sample versus findings from general population studies. The CES-D and BDI performed comparably as depression screening instruments. Both produced too many false positives when standard (low) cut-off scores were applied. However, when straight cut-off scores were used, results suggested that either the CES-D or BDI might assist physicians in reliably detecting depressed patients, without an overload of false positives. Comparison of our findings with those from other studies suggest that depression screening instruments may be particularly helpful with older primary care patients. The CES-D factor analysis highlights the need to look more closely at the relevance of positive affect to the detection, diagnosis, and treatment of depressive disorders in primary care practices.