Teachers are facing an increasing number of changes in their job context, many of which significantly affect their work lives. This study offers a theoretical understanding of the changes in teachers' working conditions, starting from the intensification thesis. The case study of a Flemish (Belgian) elementary school shows the existence of various and mutually reinforcing sources of intensification. Those sources emerge not only from outside school (e.g. policy-makers and society), but also as teachers impose their own standards on their work. The case study exemplifies the compelling (and thus intensifying) character of a collective norm of willingness to innovate. However, this norm seems to act paradoxically: both as a support in dealing with external pressure and as an intensifying factor, increasing the workload. The possibly intensifying impact of changes on teachers' working conditions is mediated by the school organization as well as the personal interpretative framework (sense-making) of individual teachers. (Contains 1 table and 5 notes.)