This paper deals with the evolution of relatively young purchasing groups. Although previous research focussed on macro-evolutionary phases of purchasing groups, no attention has yet been paid to the intra-phase developments, the so-called ‘micro-evolutions’. Insight into micro-evolutions is crucial to better understand how purchasing groups (can) develop over time. We conducted three in-depth case studies in different countries and identified five dimensions of micro-evolutions: member relationships, objectives, activities, organisation, and resources. For each dimension, we provide an overview of micro-evolutions to guide purchasing groups in developing the dimension. We conclude that the dimension ‘activities’ is very important and that purchasing groups do not have to develop the dimensions simultaneously
