Backround: An inter-institutional task force was brought together in 2018 to evaluate the irregular institutionalisation of Guarani and Kaiowá Indigenous children with disabilities in Dourados, in central-western Brazil. Aims and objectives: We draw on this case study to undertake a 'situational analysis' on the existence/absence and the use/non-use of evidence in the evaluation of public policies regarding Indigenous children with disabilities. By critically analysing concrete practices in the context of multilevel intersectoral dialogue and joint action of state bodies and civil society, we aim to highlight the effective and potential gains from using Culturally Appropriate Evidence (CAE) at the intersection of policies on children, Indigenous peoples and people with disabilities. Methods: We used a case study approach to analyse the precedents, development and ramifications of the task force, examine the legal framework regulating the rights of Indigenous children with disabilities, and describe the process of institutionalisation of Indigenous children in the Dourados region in the first two decades of the 21st century. Findings: We identified that inter-institutional and intersectoral collaboration enhances the development of CAE and the instrumentalisation of intersectoral alternatives. Discussion and conclusions: Although entrenched institutional bureaucratic culture, and the absence of mechanisms for participation and consultation with Indigenous peoples, can create obstacles to the formulation and use of these kinds of evidence in public policies, the production of evidence through the articulated and collaborative effort of agents can offer, when there are political conditions for it, the necessary conditions to develop culturally appropriate solutions for complex scenarios.