Diversity in the workplace has attracted significant interest in organisations that want to attract and retain talented employees. Breakthrough innovation requires a wider knowledge base, and organisations increasingly rely on multidisciplinary R&D teams to identify scientific developments that bridge gaps and reduce time to market. However, research on the performance implications of R&D team diversity remains limited and the empirical evidence inconsistent. This paper investigates the impact of surface and deep‐level diversity on R&D teams’ innovative performance and how diversity dimensions interact to drive innovation. We find supportive evidence that R&D team characteristics influence innovation outcomes, confirming our hypothesising that diversity is a valuable strategy for an organisation to pursue as it provides greater cognitive ability. Each diversity facet however has its own distinct effects depending on the novelty of innovation and industry. Yet, diversity is not solely positive and excessive heterogeneity could be detrimental to R&D team performance. Our findings suggest that high diversity in gender or skills in cognitively diverse teams might be negative attributes to take into consideration. Senior managers and organisations should therefore consider the appropriate mix of capabilities to benefit from creativity in diverse R&D teams and avoid possible conflict and distrust associated with diversity.