BACKGROUND: Nurse residency programs (NRPs) provide new graduate nurses (NGNs) with social support and experiential activities as a formal transition to clinical practice. AIMS: The study was conducted to answer the question: What is the effectiveness of an NRP in retaining NGNs in a psychiatric-mental health setting? METHOD: This study used a quantitative time-sequenced comparative study of multiple cohorts of NGNs hired into an NRP at a freestanding hospital in California. RESULTS: The study yielded a turnover rate of 11.7% in Year 1 (88.3% retention) and 2.9% in Year 2 (97.1% retention rate), which are lower than reported turnover rates (17.5% and 33.5%, respectively). Significant correlations are described in the workplace domains of knowledge and skills, social support, organizational citizenship behavior, civility, coping self-efficacy, organizational and occupational commitment, person-organizational fit, and burnout. CONCLUSIONS: NRPs are effective in attracting and retaining competent, confident NGNs in psychiatric-mental health nursing.