There is a paucity of theory guided longitudinal research into how carers of an adult with mental illness adapt to caregiving. This study examined changes in carer adjustment over 12 months and identified risk and protective factors using stress/coping theory. Eighty-seven carers completed questionnaires at Time 1 and 12 months later (Time 2). The risk/protective factors were background variables, coping resources, appraisals, and coping strategies. Adjustment outcomes were stable over 12 months. Stress/coping variables were associated with one or more Time 2 adjustment outcomes when controlling for initial adjustment and the direction of these associations were consistent with predictions. Findings support the application of stress/coping theory to guide identification of modifiable risk and protective factors associated with caregiver adjustment. © 2011 Wiley Periodicals, Inc. J Clin Psychol 67:1–16, 2011.