OBJECTIVE: To identify and explore concepts important to patients with cognitive symptoms of major depressive disorder (MDD) and adapt an existing patient-reported outcome (PRO) measure to assess these symptoms. METHODS: Four focus groups were conducted with MDD patients (n = 33) to elicit relevant concepts and determine whether one of several PRO scales could be used to assess cognitive symptoms of depression. Following selection and minor modification of the Perceived Deficits Questionnaire (PDQ), cognitive debriefing interviews were conducted with additional patients (n = 17) to further refine and adapt this measure for use in MDD. Minor revisions based on patient input yielded the PDQ for Depression (PDQ-D). RESULTS: Focus group participants reported a variety of cognitive symptoms that were classified into 7 general categories: lack of focus and clear thought, memory problems, difficulty with lexical access, difficulty with divided attention, difficulty with decision making, difficulty thinking quickly, and difficulty learning new things. Limitations in work productivity were the most commonly reported impacts of cognitive symptoms. While suggesting a few modifications, focus group participants reacted positively to the PDQ based on the breadth, specificity, and relevance of the items. Cognitive debriefing participants indicated that the modified PDQ items were generally easy to understand and relevant to their experiences with MDD. CONCLUSION: Because cognitive symptoms are burdensome to patients with MDD, their assessment is important to optimize treatment outcomes. The PDQ-D has the potential to supplement existing assessment methods, providing unique information important for both comprehensive evaluation of individuals with MDD and evaluation of new treatments.