Over the last two hundred years phases of overproduction and of scarcity in academic careers have recurred with a remarkable regularity. The cyclical development depends on the complex interaction between the varying determinants of growth and the varying conditions of social recruitment for specific careers. If professional prospects are favourable, careers will open up into educationally uncultivated strata, and if the prospects worsen, its recruitment basis closes a little further down again. The interplay of attracting effects (pull) and deterrence effects (push) produce the remarkable long-term pulsation of student streams in the vocational subject areas. German data from theology, law, medicine and higher education suggest that political control has effected little change in the cycle. Academic qualifications and limits on entry have always been introduced at the times of excess supply, and the history of structural change in German education is linked to these phases. © 1987, Sage Publications. All rights reserved.