Notwithstanding a number of detailed case studies, empirical evidence on the organizational development of interest groups appears to be somewhat of a blind spot in the interest group literature. No one doubts that the organizational characteristics of most interest groups have changed substantially in the latest decades. Yet, so far, systematic assessments of this claim are scarce. This lack of attention is rather odd, given the significant role researchers have attributed to organizational characteristics for explaining interest group behavior. Various features of groups, such as their media presence, influence and degree of Europeanization, have been linked with their organizational properties. Nonetheless, few scholars have examined how these organizational characteristics have changed over time, or analyzed the scope and rate of adaptation processes. In what way does the organizational development of different types of groups differ? Why did some groups become central actors in their field, whereas others lost most of their political relevance? Did similar types of groups experience parallel trajectories of organizational development, displaying stability and change at about the same moments in time? The answers to these question matter, I argue, since in a time marked by a high level of uncertainty and turbulence, versatility, the capacity to adapt, is a crucial capability of organizations
