This study had two main purposes: to examine the extent of serious mental illness (SMI), posttraumatic stress disorder (PTSD), and substance use disorder (SUD) among female inmates; and to explore the different pathways to offending for women with and without SMI. Highlights of findings from this study include the following: 43 percent of participants met criteria for a lifetime SMI, while 32 percent met criteria for SMI in the past 12 months; 82 percent of the sample met lifetime criteria for SUD, while 53 percent met criteria for lifetime PTSD; women with SMI reported greater rates of victimization and more extensive offending histories than those without SMI; and the presence of SMI significantly increased women's risk for onset of substance use, drug dealing/charges, property crime, fighting/assault, and running away. Data for the study were obtained from a sample of female offenders (n=491) from rural and urban jails. Structured diagnostic interviews were used to assess current and lifetime prevalence of SMI, PTSD, and SUD, while qualitative life history calendar interviews (n=115) were used to determine whether mental health status and trauma exposure impacted onset of different types of criminal activity and delinquency. The findings from the study indicate that women's experiences of victimization are linked to their entry into the criminal justice system, and that understanding their pathways to offending can reduce both the risk of onset for offending and the risk for continued offending. Recommendations for reducing women's risk of offending are discussed. Tables, figures, references, and appendixes