The article presents the results of an anthropological study that aims to examine the modalities of medical and social care for CALHIV, identify the various structural and social determinants of treatment failure or success, and ascertain their respective influence. The ethnographic survey was conducted between July 2020 and November 2021 in 11 of the 14 regions of Senegal and in 15 health facilities (11 health centers and 4 regional hospitals). Situations of treatment failure or success are the result of favorable or unfavorable configurations that bring into play various actors—children, parents, health care professionals—and their interactions with and in varying sociocultural and structural contexts. The studyunderscores the contribution of anthropology to the analysis and understanding of care systems. The authors argue for a differentiated approach to strengthening the skills of health facility staff, taking into account the specificity of each site.