Reducing pesticide use and its risks has become a major policy objective across Europe. Current calls for corresponding change in the agricultural system are increasingly framed in the context of sustainability transitions. Building on sustainability transitions research (STR), this dissertation approaches agriculture as a socio-technical system. A core issue in STR is the dialectic relationship between stability and change. The thesis focuses on processes of stability and change in three key system dimensions – practices, discourses, and policies – and investigates what elements and dynamics in these dimensions hinder, enable, or shape a sustainability transition toward low-pesticide agriculture. To contribute to a better understanding of complex agricultural transition processes, the thesis bridges theoretical and methodological approaches rooted in different disciplines. First, it draws on social practice theory to develop an understanding of pesticide use as a routinized social practice and to examine the interplay of individual and structural agency in crop protection practices. Second, a discursive approach is taken to explore the discursive struggles evolving around pesticide use and its legitimacy and how they contribute to opening or closing transition pathways. Third, using a policy change perspective, the thesis identifies common reasons for agricultural policy reform failures. Empirically, the thesis focuses on the case of a low-pesticide transition in Switzerland. It employs a mixed methods research design, combining qualitative methods of data collection and analysis (content analysis of semi-structured interviews, argumentative discourse analysis, document analysis, participant observation) and quantitative methods (statistical analysis of survey data, text mining). Based on the findings from four papers that make up this cumulative dissertation, three main insights into the emerging transition toward low-pesticide agriculture are distilled. First, the agricultural regime resists fundamental change and fosters a regime-stabilizing pathway of incremental change and risk reduction. Second, crop protection practices are the locus of continuous incremental change, but it remains unclear whether this can enable fundamental change. Third, shifts in the socio-technical pesticide system will likely be characterized by diversity and transition policies must account for this diversity. Overall, the research conducted for this dissertation highlights the context-dependence and unpredictability of many change processes in agriculture. It cannot be known whether the current incremental changes, combined with disruptive events, will indeed contribute to a fundamental transition process. Nevertheless, the ongoing change processes in the crop production and pesticide system feature a number of characteristics that are necessary preconditions for a transition. This dissertation sheds light on such preconditions and contributes to strengthening the field of agricultural sustainability transitions research more broadly. It does so by adding a practice-based perspective on stability and change in the pesticide system, by advancing the understanding of the role of discursive elements in pesticide policy and regime change, and by contributing to understanding agricultural policy reform failures that are linked to regime resistance.