This chapter presents and discusses some methodological issues in the application of stochastic actor-oriented modeling for longitudinal network analysis. By following a forward-selection procedure, three models will be defined and run on four observations of the collaboration network subsidized by the European Union Framework Programmes in the Aerospace sector, covering a 20-years time span (1994-2013). Specifically, the influence exerted by five dimensions of inter-organizational proximity (geographical, organizational, social, institutional and technological) on the longitudinal evolution of the network is analyzed. Results show that organizational proximity is the most important driver for the longitudinal evolution of the network. Further, this form of proximity is constant in time, analogously to the geographical one which, on its side, only moderately affects network's evolution. Network proximity plays a weak but positive influence, while the institutional and technological dimensions do not affect the evolution of the network. Anyway, when proximity is evaluated on single institutional and technological types, different roles are detected. Organizations' patenting activity, introduced as a control variable, does not play a significant role on network's evolution.