This preliminary study investigated the association of insight (defined as a patient's recognition of having a mental illness) with depression and suicidality among individuals with schizophrenia (N = 1009), bipolar I disorder (N = 297), and recurrent major depression (N = 162). Participants completed interviews at 2 time periods, 6-months apart. Individuals who were recognized having a mental illness reported significantly greater depression than those who denied having a mental illness. Recognition of mental illness was significantly related, both retrospective and prospectively, with suicidal ideation and attempts. No significant differences were found between the diagnostic groups in these relationships. Although there are many clinical benefits associated with insight, these findings suggest there may possibly be cause for concern in attempting to increase insight among individuals with a serious mental illness. However, current evidence suggests that certain forms of treatment may be beneficial in improving insight, while resulting in a decrease in negative affect, rather than an increase.