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 = 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.