ObjectiveTo evaluate the effectiveness of a leadership and management program in aged care. DesignDouble-blind cluster randomized controlled trial. SettingTwelve residential and community-aged care sites in Australia. ParticipantsAll care staff employed for 6 months or longer at the aged care sites were invited to participate in the surveys at 3 time points: baseline (time 1), 9 months from baseline (time 2), and 9 months after completion of time 2 (time 3) from 2011 to 2013. At each time point, at least 500 care staff completed a survey. At baseline (N = 503) the largest age group was 45 to 54 years (37%), and the majority of care staff were born in Australia (70%), spoke English (94%), and had at least completed secondary education (57%). InterventionA 12-month Clinical Leadership in Aged Care (CLiAC) program for middle managers, which aimed to further develop their leadership and management skills in creating positive workplace relationships and in enabling person-centered, evidence-based care. Main outcome measuresThe primary outcomes were care staff ratings of the work environment, care quality and safety, and staff turnover rates. Secondary outcomes were care staff's intention to leave their employer and profession, workplace stress, job satisfaction, and cost-effectiveness of implementing the program. Absenteeism was excluded due to difficulty in obtaining reliable data. Managers' self-rated knowledge and skills in leadership and management are not included in this article, which focuses on care staff perceptions only. ResultsAt 6 months after its completion, the CLiAC program was effective in improving care staff's perception of management support [mean difference 0.61, 95% confidence interval (CI) 0.04–1.18; P = .04]. Compared with the control sites, care staff at the intervention sites perceived their managers' leadership styles as more transformational (mean difference 0.30, 95% CI 0.09–0.51; P = .005), transactional (mean difference 0.22, 95% CI 0.05–0.39; P = .01), and less passive avoidant (mean difference 0.30, 95% CI 0.07–0.52; P = .01); and were rated higher on the overall leadership outcomes (mean difference 0.35, 95% CI 0.13–0.56; P = .001) as well as individual manager outcomes: extra effort (P = .004), effectiveness (P = .001), and satisfaction (P = .01). There was no evidence that CLiAC was effective in reducing staff turnover, or improving patient care quality and safety. ConclusionsWhile the CLiAC leadership program had direct impact on the primary process outcomes (management support, leadership actions, behaviors, and effects), this was insufficient to change the systems required to support care service quality and client safety. Nevertheless, the findings send a strong message that leadership and management skills in aged care managers can be nurtured and used to change leadership behaviors at a reasonable cost.