This paper presents a simultaneous model for the joint decisions of working, studying and leaving the parental household by young people in Spain. Using cross-section data from the 1990–1991 Encuesta de Presupuestos Familiares, the model is estimated by a two stage estimation method. Endogeneity of the three decisions proves to be important in order to understand the dynamics of household formation. Our results also confirm a number of plausible intuitions about the effect of individual characteristics and economic variables on these decisions, and provide some new insights into the reasons for young people in Spain remaining in large numbers in the parental home. Most of the results are gender independent.