The puzzling coexistence of inertia and flexibility in the Russian labor ma
rket are explained using a segmentation model. By placing uncertainty at th
e center of decision-making by both firms and employees, this article shows
that workers, all of whom an risk averse, may adopt behaviors differentiat
ed according to their productivity. Some of them, with favorable job prospe
cts, become mobile and enter into contracts whereby their pay varies depend
ing on their productivity. Others, with less favorable opportunities accept
lower wages in exchange for job security and fringe benefits (the firm's s
ocial services). This model suggests an interpretation of wage arrears as p
art of the implicit "insurance contract" between the firm and certain wage-
earners. The model's predictions are tested by using a database of 13.628 R
ussian companies observed from 1992 to 1997.