In recent years, the Chilean Child Welfare Service has been questioned by the legislative and judicial powers over its work with children and their families. However, it remains unclear what the social workers' family conceptions are and how they influence professional judgment. Here, 85 social workers were interviewed, and four focus groups were conducted. The interactions between variables were estimated using ANOVA and a model with marginal measures was developed with the purpose of observing the differences between groups for each factor, followed by post hoc comparisons. The qualitative data was examined by content analysis. We detected the presence of a marked tendency in professionals being able to visualise families based on their weaknesses. Case supervision and the knowledge of previous cases are the main factors that influence family conceptions.