The productivity of enterprises is an important indicator, for individual enterprises as well as for policy makers. For individual firms, their productivity is a main determinant of their performance, while the aggregate productivity is one of the main determinants of economic growth. In this study we examine the relationship between the age of firms and the level and growth rate of productivity, focusing on firms of at least 10 years of age. For these firms, we will examine the following two research questions: How does the distribution of firm productivity (as characterised by mean and standard deviation) change over age cohorts? To which extent are differences in productivity between individual firms related to firm age?