<p>Drawing on Social Exchange Theory (SET) and the Resource-Based View (RBV), this study explores how perceived training effectiveness is related to team performance through diversity management and teamwork quality. Data came from 215 employees of an Indonesian state-owned enterprise, selected through stratified random sampling and analysed using AMOS Structural Equation Modelling. Employees who regarded the training as effective also reported stronger diversity management; stronger diversity management was associated with better teamwork quality, which in turn was associated with higher team performance. The direct path from training effectiveness to teamwork quality was not statistically significant. Instead, training was linked to team performance through the sequential strengthening of diversity management and teamwork quality. This pattern suggests that training is more likely to influence team outcomes when it is embedded in inclusive practices and ongoing collaborative routines. SET interprets training as organisational support that can encourage reciprocity, trust, and participation, whereas RBV frames diversity management and teamwork quality as valuable team capabilities that are difficult to replicate. For public organisations in developing economies, the findings point to HR strategies that connect training content with diversity goals and team development. In practical terms, programmes that build trust, fair treatment, and team cohesion may provide a more reliable route to effective team performance.</p>