dc.title: Where do faith based organizations go? Supply-side geographic distribution of FBO humanitarian presence in Nigeria Northeast and the Democratic Republic of Congo dc.description.abstract: Faith-based organizations make up a significant share of the humanitarian system in sub-Saharan Africa, yet systematic evidence on where they concentrate, which sectors they serve, and whether they track the religious composition of affected populations remains scarce. This report tests three competing supply-side hypotheses: gap filling, sector specialization, and co-religionist alignment, using OCHA 3W operational presence data for northeastern Nigeria and the Democratic Republic of Congo. The analysis draws on over 57,000 organization-location-sector records across 70 Local Government Areas and 156 territoires spanning 2015 to 2025. I develop a five-pass faith classification procedure grounded in the FORFA framework, estimate OLS regression models with HC3 robust standard errors, and conduct chi-square tests of sector independence. The gap-filling hypothesis is rejected in both countries. Faith-based organizations cluster with secular actors rather than filling geographic voids, and the positive coefficient on log total organizations replicates across both cases. The sector specialization hypothesis is supported in both countries, with faith-based organizations systematically overrepresented in community relational sectors and underrepresented in technically intensive ones. The co-religionist alignment hypothesis produces contrasting signs, negative in Nigeria and positive in DRC. The Nigeria result reflects Christian FBO concentration in a Muslim-majority displacement zone. The DRC result reflects Catholic institutional path dependence rather than identity-based deployment. Across the two cases, the analysis finds no support for gap filling, no consistent support for co-religionist alignment, and strong support for sector specialization as the most robust predictor of FBO distribution. Co-religionist alignment is not a universal mechanism but a context-dependent one shaped by religious demography and institutional history.