In 2003, 19% of persons who worked in intermediate occupations five years earlier no longer formed part of this socio-occupational category, up from 12% in 1985. Of all the official French socio-occupational categories, “intermediate occupations” is the one that displays the highest socio-occupational fluidity, i.e., the one whose members change categories most frequently. The two most common types of exit paths from intermediate occupations are: (1) entry into the “managers and higher intellectual occupations” category—in other words, upward socio-occupational mobility; (2) entry into the “manual workers” group and, especially, the “lower-grade white-collar [clerical] workers” group—in other words, downward socio-occupational mobility. Between 1985 and 2003, the probability of upward mobility has risen. But the phenomenon has been accompanied by a sharp increase in downward mobility. The probability of experiencing mobility varies considerably across intermediate-occupation sub-categories, bounded, at one end, by high immobility among healthcare and social-work occupations, and, at the other end, by significant mobility for administrative and commercial intermediate occupations in firms. Educational attainment has a very powerful influence on intermediate-occupation paths: in 2003, 12% of persons in intermediate occupations who had higher-education degrees in 1998 experienced upward mobility, while 5% experienced downward mobility. For workers without higher-education degrees, the proportions were 6% and 13% respectively. All other things being equal, men experience upward mobility far more often than women, and downward mobility far less often.