the article relies on the analysis of Social Networks in order to compare the networks at work in the composition of thesis committees between 2003 and 2008 in a French provincial university in three very different disciplines-astrophysics, archaeology and economics-so as to test the hypothesis that connections actually pre-existed to graduation. Were members co-authors of scientific publications or were committees constituted only for the sake of awarding a PhD? Astrophysics and its "equipment" ethos is the one to superimpose most often committee membership and co-publishing. Archaeology falls somewhere in-between, due to the greatest scarcity of committee members. Last of the three, economics actually separates the two types of collaboration by most frequently inviting international researchers.