This study aims at analysing the evolution of job stability in the Spanish labour market during the period 1987-2003 and investigating the groups (defined by individual and job characteristics) who have experienced the greatest instability. Information comes from the Spanish Labour Force Survey (Encuesta de Población Activa, EPA) microdata used as a crosssection. Results suggest, first, that job instability is very high in many of the analysed groups; second, that job instability has undergone continuous growth from the late 1980s, associated with the rise of the number of contracts, the opening of the economy and the existence of high unemployment rates; finally, that certain groups (women –mainly with children under 6–, the young, workers with a low educational level and workers in low-skilled jobs) have suffered the largest rises in job instability.

Key words: job tenure, job stability.
JEL classification: J21, J23.