Depending on the national context school principals are more or less used to continuous development. The initiative for development can come from different sectors such as professional organizations or research studies, or different levels such as national or local initiatives. In Sweden several initiatives for development of teaching have been initiated since 2010, due to lower test results in mathematics (PISA and TIMMS) and based on research. Therefore, an increase in teaching hours for mathematics in compulsory school was decided on a national level in 2012. The aim of the study is to present and discuss how principals coped with this change. As the change mostly concerned grades 1–3 (primary school pupils age 7–9), principals responsible for this level were interviewed and also answered an e-mail questionnaire. The findings show that the principals gave priority to organizational changes. All schedules for teachers, for pupils, sometimes for recreational instructors and even for school buses had to be revised. Continuing education in mathematics for the teachers was also promoted by the principals. All changes were accepted by principals, staff and parents. In contrast, few pedagogical issues were otherwise brought up and the follow-up to the change was not systematic. The different levels in a steering chain show that all levels trust that the next level, or the level above, should carry out their duty concerning organization. On the other hand, the entire national initiative with time allocation and continuing education can be perceived as distrust in how the local level and professionals have handled the development of teaching math.