This chapter deals with the two main ways of extending the length of the productive working day or week. It explores the changes taking place in shiftwork patterns, including the progressive extension of shiftworking and the signs of development of new shiftwork systems. Overtime is a long-established practice, as is the evidence of disputation over the working of overtime. The union was particularly critical of systematic forms of overtime being worked even when trade was slack which was seen to exacerbate the unemployment problem among engineering workers. The NBPI similarly reported in 1970 that the commonest reason cited by management for working overtime was to deal with normal operating requirements; in more than half of companies surveyed, a main reason for overtime working was to meet the normal level of demand. In Britain and elsewhere the causes of overtime working are in part similar to those which have given rise to increased shiftwork.