Insomnia is strongly associated with certain mental health problems in the general population. However, there is little research examining this relation in young adults-an age group where many mental health problems first present. This study examined relations between insomnia and mental health symptoms in a college population (N D 373; 60.9% women; mean age of 21 years). Insomnia was assessed via self-report and sleep diaries, and mental health was assessed via the Symptom Check List-90. Analyses revealed insomnia was prevalent (9.4%), and these young adults had significantly more mental health problems than those without insomnia, although some significant results were lost after controlling for comorbid health problems.