© 2014 American Psychological Association. Objective: Individuals with serious mental illness (SMI) are dying on average 25 years prematurely. The leading causes are chronic preventable diseases. In the context of a tobacco-treatment trial, this exploratory study examined the behavioral risk profiles of adults with SMI to identify broader interventional needs. Method: Recruited from five acute inpatient psychiatry units, participants were 693 adult smokers (recruitment rate - 76%, 50% male, 45% Caucasian, age M = 39, 49% had income < $10,000) diagnosed with mood disorders (71%), substance-use disorders (63%), posttraumatic stress disorder (39%), psychotic disorders (25%), and attention deficit- hyperactivity disorder (25%). The Staging Health Risk Assessment, the primary measure used in this study, screened for risk status and readiness to change 11 health behaviors, referencing the period prior to acute hospitalization. Results: Participants averaged 5.2 (SD = 2.1) risk behaviors, including smoking (100%), high-fat diet (68%), inadequate fruits/vegetables (67%), poor sleep (53%), physical inactivity (52%), and marijuana use (46%). The percent prepared to change ranged from 23% for tobacco and marijuana to 76% for depression management. Latent class analysis differentiated three risk groups: the global higher risk group included patients elevated on all risk behaviors; the global lower risk group was low on all risks; and a mood and metabolic risk group, characterized by inactivity, unhealthy diet, sleep problems, and poor stress and depression management. The global higher risk group (11% of sample) was younger, largely male, and had the greatest number of risk behaviors and mental health diagnoses; had the most severe psychopathologies, addiction-treatment histories, and nicotine dependence; and the lowest confidence for quitting smoking and commitment to abstinence. Conclusion: Most smokers with SMI engaged in multiple risks. Expanding targets to treat co-occurring risks and personalizing treatment to individuals' multibehavioral profiles may increase intervention relevance, interest, and impact on health.