Conventional studies of absenteeism concentrate on labor supply. An equilibrium approach, however, establishes that the shadow cost of absenteeism varies across firms that operate different technologies. Using an unusual employee/employer matched data set from France, which records both individual worker absenteeism and information about technology, we show that firms operating just-in-time technology have higher shadow costs of absence than firms that do not. The estimates are used to calculate the economy-wide cost of absence, which turns out to be very low. (JEL J22, J31, J41)