Children’s subjectisuppleve well-being (SWB) constitutes an important component in the understanding of their quality of life and refers to the opinions and evaluations made by children themselves about the main aspects of their lives, and their satisfaction with these life aspects. This research focused on children whose SWB has been little investigated. In Spain, 38% of children in out-of-home placements are in residential care, 46% in kinship care and 16% in non-kin foster care. The aim of this study was to analyse SWB among adolescents in care, considering the type of placement in greater depth and how it correlated with several explanatory variables. We adapted the International Survey of Children’s Well-Being questionnaire for adolescents in care aged 12–14 years old, including 3 psychometric scales on SWB: Overall Live Satisfaction, the Students’ Life Satisfaction Scale, and the Personal Well-being Index—School Children. The response rate was 58% (N = 700). Multiple regressions were used, an open question was also included and categorical content analysis was done. Results indicated that adolescents in foster care (kinship and non-kinship) reported better SWB in all life domains than those in residential care. Variables, such as the number of placements, the amount of time spent in the last placement, a previous failed foster placement and satisfaction with caregivers had an impact on adolescents’ SWB. Links between these results and those obtained in the qualitative analysis were particularly notable as regards relationships with the people who lived with them, placement instability, and lower life satisfaction among adolescents in residential care.