This article reviews and calls attention to the work underlying significant improvements in the conceptualization, measurement and analysis of the third sector on a comparative basis worldwide that have been made over the past three decades. This article provides an update on the current status of each measurement instrument, their institutionalization in the world’s major official statistical systems, and describes how they can work in concert to provide regular, robust, and accurate information about the third sector at the national level around the world. This article also represents a call to action for the research community to advocate for having these research tools implemented in their own countries, to protect the progress made, to support and provide oversight of their implementation, to use the resulting data in their own research, and to initiate improvements in the development of these tools in the future. Doing so will grow the base of cross-nationally comparable data on the third sector, will provide lenses for us to better see the features that make the civil society sector in each country distinct, and will open the way for vastly expanded empirically grounded theory-building in this field.