In the present paper, we analyse the association between the skill composition of young firms and the firms’ subsequent survival. This is made possible by means of a matched employer-employee dataset from Statistics Sweden on a cohort of firms that started between 2001 and 2003. Our findings show that, compared to firms that exit, the firms that survive at least until 2012 have teams with higher complementarity at the start, and successively increase their skill complementarity over time. Subsequent discrete time hazard models, controlling for several well-known determinants of firm longevity, show that complementarity plays a crucial role for firm survival. Higher skill synergy within firms, as compared to high degrees of substitutability, is associated with a lower conditional probability of failing. The role of skill complementarity is stable across different specifications and outweighs many other determinants of firm survival, such as starting size and experience of the founder.