The initial outright rejection of shorter working hours by many employers has been replaced by their sustained campaign to recoup lost time by raising the work intensity of their employees and its impact on fixed capital. But longer working hours imposed in some countries as part of the neoliberal globalized attack on the living standards of workers since the 1980s, have called into question both marginalist and Marxist explanations of the reasons behind falling and rising working hours. This article investigates-from a Marxist standpoint-the combined impact of shorter working hours, rising productivity and labour intensity both theoretically and in practice, during the first two decades of this century in Chile. This article investigates the probable impact on the economy and its division into wages and profits, of a cut in the working week and changes in labour flexibility.