This paper investigates the contribution of high-growth firms (HGFs) to aggregate productivity growth. Four stylized facts emerge. First, HGFs mainly contribute to productivity growth only during their high-growth phase but not afterwards. Second, the contribution during this phase varies substantially across industries and it is not necessarily positive. Third, the impact on productivity depends on how HGFs are defined. Output-based HGFs substantially outperform employment-based ones in terms of their productivity contribution while the difference between the two firm groups is much lower in terms of job creation. Fourth, HGFs’ contribution to productivity is higher in industries where industry dynamics favor growing firms, captured by the strength of reallocation and the relationship between productivity growth and size growth. We present a simple model to show that these patterns arise naturally under realistic correlation structures. Taken together, these results suggest that specific policies supporting HGFs may focus on firms which increase their sales, and HGF policies can effectively be complemented by more general framework policies promoting efficient reallocation.