The development of effective and sustainable economic policies for Tanzania requires access to appropriate databases. One such database is a social accounting matrix (SAM) that details the structure of the entire economy, taking into account the patterns of production and demand, and various institutional relationships. Prior to this study the most recent SAM for mainland Tanzania was for 1992 and was based on past household budget and labor force surveys. Following the release of newer versions of these two surveys as well as a new input-output table for 1992, it is desirable to construct a new SAM for the country. Furthermore, given that Tanzania is committed to reducing national poverty, it is necessary that this new SAM is able to address questions related to poverty and inequality. This paper outlines the process of developing SAMs for mainland Tanzania. Although this process was formally a collaborative project undertaken by the International Food Policy Research Institute (IFPRI) and the Tanzanian National Bureau of Statistics (NBS), the final project team also contained representatives from the Bank of Tanzania, the Tanzanian Revenue Authority, the University of Dar es Salaam, and the Economic and Social Research Foundation (ESRF). The collaboration combined IFPRI’s technical experience with the collaborators’ knowledge of the country and available statistical data. The SAMs were constructed during a series of workshops held in Tanzania aimed at capacity building, information sharing, and firsthand data validation. Furthermore, the process was made sufficiently flexible to allow the NBS to easily update the SAM to subsequent years. The updating process is also detailed in this paper. Although only the 2000 SAM is described, the process is identical for the other Tanzanian SAMs published by IFPRI for 1998 onwards.