Strategic human resource management theory suggests that diversity and equality management (DEM) systems provide a firm with a competitive advantage, leading to superior performance. This study proposes and tests a moderated mediation model focusing on antecedents (i.e. top management team gender diversity) and consequences (i.e. performance) of DEM systems in the context of lower through middle management (LTMM) gender diversity. The model was tested in 248 medium-to large-sized organizations using time-lagged survey and archival data. The findings provide full support for the hypothesis that a gender-diverse top management team is positively associated with DEM systems. The results provide partial support for the following hypotheses: DEM systems are positively associated with performance and this relationship is moderated by LTMM gender diversity; and DEM systems mediate the relationship between TMT gender diversity and performance. We discuss theoretical, research and practical implications.