Research on foster care shows a growing interest in knowing what factors exert influence on success or failure of the placements. Several studies have analysed the variables that influence the outcome of family foster care. The main variables addressed by these studies were behaviour problems and impulsivity/inattention in foster children, warmth/communication, parenting style, and level of burden in the foster parents. This study aimed to determine whether distinct profiles can be identified among foster placements with common characteristics, and also sought to define a predictive function for the success or failure of foster care. Participants included foster children and their respective foster families. The sample comprised 104 non-kinship foster children in long-term foster care (56 boys and 48 girls) whose mean age at the time of data collection was 11 years. These children were being fostered in 86 families, corresponding to 71 foster fathers and 86 foster mothers. Access to foster families and information about the foster placements was authorized and provided by the Child Protection Agency in Andalusia (Spain). A quantitative methodology was used during both the collection and the data analysis. A k-means cluster analysis identified three clusters, corresponding to high-, moderate-, and low-risk placements. The variables that formed part of these clusters were behaviour problems and impulsivity/inattention in foster children, level of burden in the foster parents, an authoritarian parenting style, and criticism/rejection by the foster parents. A discriminant analysis confirmed the differences between the three clusters and enabled us to create a function for classifying cases in each group. These results can be used to identify at-risk placements and may help to avoid situations that could undermine the foster child’s development. The findings could also be useful in terms of assessing the suitability of foster families, as well for identifying their training needs.