Research collaboration is studied in different research areas, so as to provide useful insights on how researchers combine existing distributed scientific knowledge and transform it into new knowledge. Commonly used metrics for measuring research collaborative activity include, among others, the co-authored publications (concerned with who works with whom) and the citations (concerned with who cites who). Within this context, in this paper, we focus on the co-authorship network of researchers who collaborate in Technology-enhanced Learning (TeL). This is achieved through the example of the "Educational Technology & Society" (ETS) Journal, where Social Network Analysis (SNA) metrics are applied for analyzing the co-authorship network of the journal. The results of our analysis provided us with evidence that the key authors of ETS Journal co-authorship network have a Taiwanese national background and they have established a strongly connected group that collaborates frequently, diversely and widely. Both authors and collaborations of the ETS co-authorship network have been polynomially increasing during the past 15 years and the co-authorship network has probably arrived at its "phase transition," which means that it is expected to start becoming more connected in the coming years.