A study is reported where the introduction of teamworking was accompanied by negotiated changes in working time patterns, involving some employees transferring to a 5-shift, 8-hour pattern, others to a 5-shift, 12-hour pattern. Employee attitude surveys before and after the changes show those moving to 12-hour working much more satisfied with both working time and other changes, compared with those remaining on 8-hour shifts. The creation of extra non-work days was seen as the major advantage of the longer shifts, which compensated for the harder work regime identified under teamworking and the greater rigidity of the 5-shift system. The findings underline the potential significance of working hours for employee support for broader changes in working practices. Possible explanations of why the longer shift pattern met with considerable support at one research site, but failed to gain support at a similar site elsewhere, are also explored.