An RCT was used to investigate the effectiveness of an innovation support scheme (ISS) for SMEs in tackling age diversity challenges. The ISS included leadership training aimed at fostering team climate and valuing age diversity, and computer-based cognitive training for employees. Levels of recruitment into the trial, engagement in the interventions and response rates to surveys were lower than anticipated, which have all limited the potential to identify the impacts of the interventions. Nevertheless, the findings suggest that leadership training effectively fostered psychological safety climate, a predictor of innovative behaviors and creative engagement. However, the mechanisms remain unclear, with self-efficacy moderating the link between training and leadership behaviors. Cognitive training showed limited effectiveness, offering a marginal improvement in divergent thinking.