Most of the criteria for competence in current use emphasize cognitive rather than affective dimensions. Our clinical experience indicates that affective disorders may impair competence in a detectable and identifiable way. In particular, patients with major affective disorders can retain the cognitive capacity to understand the risks and benefits of a medication, yet fail to appreciate its benefits. A case study of a pathologic grief reaction is introduced to illustrate how cognitive and affective impairments may coexist and require separate remedial strategies for restoration. Further empirical work on the role of affective disorder in impairing competence is warranted and planned.