People act in the light of their beliefs, yet sociological theories of acti
on have been weak in explaining why people hold the beliefs they do. I prop
ose a means of integrating beliefs into rational choice theory using a Baye
sian learning model in which people act in accordance with the beliefs they
hold about the world. By observing the outcomes of their actions they modi
fy their beliefs. This approach, in contrast with many others, recognizes t
hat beliefs evolve in the light of experience. The approach is applied to s
how how the evolution of beliefs about the returns to effort in education c
an give rise to observed patterns of class differences in educational expec
tations and so to class differences in mobility chances, at least as these
are mediated through educational attainment. I discuss the general issue of
learning in the Bayesian approach and outline some limitations and areas o
f further research.