The WSIS + 10 (ten years after the World Summit on The Information Society) environment culminating in a December 2015 meeting at the United Nations in New York provides an opportunity for a longitudinal view of international organizations in internet governance over the last tumultuous decade. This paper reports on findings from an ongoing three-year study of select international organizations (such as the UNESCO, the OECD and the Council of Europe) acting in the internet governance policy spaces. Originally convened by the United Nation’s system in 2003 and 2005 and convened again in December 2015 by the same system, the ten years period result of the regulatory-related configurations emerging from the initial WSIS meetings shows major transformations in both the actual policy spaces and the type of collaborations and conflicts. This paper uses document analysis, interview data, and participant observation as methods in tracking and analyzing these trajectories of change (including at the level of an international organization itself). At the same time, it tracks and analyzes emergent collaborations and conflicts among other actors (nation-states, civil society, the private sector, academe and the technical community) interacting in international organization-related contexts. Building on previous in-depth research on individual actors and specific issues at stake, this paper pays particular attention to data gathered from Fall 2015 meetings both of the preparatory processes for the United Nations Meeting and at the tenth IGF (Internet Governance Forum), with a view to assessing 10 years of multistakeholder governance in the Internet field.