This paper addresses the influence of heterogeneity on the creativityperformance of formal and informal groups when generating innovation ideas.Data on all innovation ideas generated at a company during three years havebeen gathered and analyzed. The empirical results showed that heterogeneityin formal groups has a positive influence on the quality of the ideas generated.However, after a certain amount of heterogeneity the performance drasticallydecreased, showing that there is an optimum for when heterogeneityinfluences the performance of the formal groups positively. The informalgroups did not show the same results.Managerial implications of the findings are that both the strategic input toideation and its organizing need to be considered.