We examine why and when proactive personality is beneficial for innovative behavior at work. Based on a survey among 166 employees working in 35 departments of a large municipality in the Netherlands we show that an increase in task conflicts explains the positive relation between a proactive personality and innovative employee behavior. This process is moderated by job autonomy in such a way that the relationship between proactive personality and task conflict is particularly strong under low compared with high autonomy. The present research contributes to the discussion on the potential benefits of task conflict for change processes and highlights the importance of examining the interplay between personality and work context for understanding innovation practices.