Most models that analyse risk and protective factors during adolescence include the family system and family functionality as key elements. For this reason, Family Counselling Services play an important role in addressing adolescent problems. These services require quick and easy-to-apply assessment tools that integrate different dimensions of family functioning. To develop and validate a brief scale for use in Family Counselling Services, exploring and confirming its factorial structure and testing its psychometric properties. Confirmatory Factor Analysis using structural equation modeling. 441 family members in seven units. Results: A 5-factor structure was confirmed, with a good fit. All the Average Variance Extracted values were higher than the Maximum Shared Squared Variance values. The results confirm the structure of the Family Functioning Scale-Madrid. In addition, the scale demonstrates adequate psychometric properties and stable structure during two evaluation periods with different samples. The instrument is considered reliable and consistent for of assessing family intervention carried out in Family Counselling Services.