OBJECTIVES: 1) to identify concepts relevant to patients when  measuring cognitive symptoms of depression and their impacts, and 2) to adapt an existing patient-reported measure of cognitive function for MDD. METHODS: Four age-stratified focus groups (total N = 33) were conducted with adults under treatment for MDD. Following open concept elicitation, participants provided feedback on two self-report measures of cognitive symptoms: the Applied Cognition General Concerns Scale (Gerson et al., 2006) and the Perceived Deficits Questionnaire (PDQ) (Sullivan et al., 1990). Focus group results led to a modified PDQ for MDD. Two sets of cognitive interviews with additional MDD patients (N = 17) refined the instrument, resulting in the PDQ for Depression (PDQ-D). RESULTS: Focus group participants reported seven different categories of cognitive symptoms.  Across the age strata, the most bothersome were difficulties with concentration, attention and memory. Patients described many ways their cognitive symptoms affected them; productivity limitations were among the most salient.  While most focus group participants deemed the PDQ content appropriate, a shorter reference period and more explicit response options were suggested. Cognitive interview results suggested that the initial version of the 20-item PDQ-D was an appropriate and comprehensive assessment of cognitive symptoms of MDD. Interview participants found the items easy to understand and answer. Minor modifications made in early interviews facilitated completion of the measure in later interviews. CONCLUSIONS: The PDQ-D is a patient-reported assessment of cognitive function with potential to provide unique information important for comprehensive evaluation of individual patients with MDD and new treatments for this disorder.