The analysis of employees’ labour-market paths cannot be confined to the characterization of their individual profiles. The characteristics of the jobs they have held in the past are also important determinants of their later occupational mobility. We seek to determine the variables (of an individual kind, or relating to earlier jobs) that influence the security of occupational paths, with “security” assessed on three criteria: employment stability (keeping the same job), employment security (rapid return to work after a mobility spell outside the firm), and income security (maintaining or increasing one’s income after mobility). Our analysis covers the period 1998-2003 using the 2003 “Training and Occupational Skills” (Formation et Qualification Professionnelle: FQP) survey. The characteristics of the job held in the past have a particularly strong influence on the continuity of the tie between an employee and a firm, and on the rapid resumption of a job after a spell of external mobility. As regards income security, the factors depend on whether the mobility is internal or external. For external mobility, the effect of the type of job outweighs that of the individual variables, which is not the case for internal mobility. We can thus discern a range of highly distinct mobility spaces: from in-house careers combining job and income security to upward external paths offering income growth. In between, we find forms of mobility that are risky because they expose workers to long-term unemployment or income losses. The influence of past-job characteristics on the security of these paths turns out to be crucial.