Numerous studies have emphasized the necessity for major transitions in agriculture. Organic farming is presented as a way to limit the environmental impact of agriculture and produce healthier food. While studies often compare the performance of organic farming to that of conventional farming, there is a lack of knowledge on the conversion period. The present work explores the dynamics of practices employed during the conversion to organic farming and the impact of this transition on various compartments of the agrosystem. From 2013 to 2016, a regional agronomic diagnosis was performed on a network of 48 vineyard plots * year situations in southern France that are either under conventional management or are transitioning to organic farming. An inventory of practices was performed, and various indicators for the agrosystem status were monitored to investigate the changes that occur during the conversion to organic farming. The results of this study showed that the conversion involves a transitional period during which practices change and are adjusted from year to year. All the compartments of the agrosystem studied are impacted by these changes. Yield reductions observed in the first and second years of conversion could be related to the dynamics of pest and disease severity, decreases in nitrogen status and increases in water stress. Pest and disease control and soil management are key practices that must be mastered to limit the impact of conversion on production. This study shows that knowledge and in-depth support are needed before and during conversion to limit the impact of this transitional period and make the conversion successful.