PIP: This study sought to ascertain, from census and other data, the number of people living on state-claimed forest land (SCFL) in West Kalimantan in the outer islands of Indonesia. One aim was to determine why data collection is problematic. In 1990 the outer islands accounted for 38% of total population, 93% of its land mass, and 98% of its forests. 72% of the land mass of the outer islands was designated SCFL. Kalimantan has 38.5 million hectares of SCFL, while West Kalimantan has 9.2 million hectares, or 63% of the land area of the province. In 1990, 3.2 million people lived in West Kalimantan. Two sets of forest cover maps and census statistics at the village level were integrated into the geographic information system (GIS) technology by district and regency boundaries and the location of villages. The fieldwork was conducted in Sengah Temila District in Pontianak Regency and Simpang Hulu District in Ketapang Regency. Four methods were used to estimate forest populations: 1) estimating gross population density, 2) mapping forest villages, 3) adjusting density to account for uneven population distribution, and 4) estimating population densities for specific villages and generalizing to the province level. Methods 3 and 4 gave the most reasonable estimates. Population varied from 650,000 to 1 million. Government census statistics proved to be accurate representations of human population. The 1:50,000 scale of topological maps of West Kalimantan correctly identified the location of villages listed in the census. The Indonesian Ministry of Forestry's forest-planning maps and the RePPProT maps both reported similar SCFL. The GIS technology was useful in integrating data from several sources. The lack of knowledge was not due to political or institutional interests.