NGOs comprise over half the cumulative number of delegates attending the United Nations Framework Convention on Climate Change (UNFCCC) Conference of the Parties (COP) for the 1995–2009 period. These NGOs represent a wide array of issues, including sustainable development, business, and higher education, to name just a few. Based on UNFCCC publicly available participation statistics, this article analyzes NGO participation from a quantitative issue-based perspective, and compares the results with the relevant conclusions drawn by the other contributors to this special issue. The findings of this analysis confirm informed expectations about issue-driven NGO participation. In particular, three main findings are that: (1) environment and conservation, academic, business, and energy NGOs dominate civil society participation in the UNFCCC; (2) UNFCCC constituencies do not adequately capture the range of issues addressed by observer NGOs; and (3) since 2007, NGO participation has sig-nificantly increased and diversified.