In the current context of increasing climate instabilities and new pest pressures, in situ crop diversity has been recognized as a relevant way to lower the genetic vulnerability of a crop. Before implementing any future deployment of within-crop diversity in agricultural landscapes, a detailed knowledge of the main drivers that affect the spatio-temporal structure of crop diversity appears necessary. Our study was primarily carried out to identify the drivers of bread wheat diversity at fine spatio-temporal scale in France over the period 1981-2006 by accounting for acreage frequencies and allelic composition of varieties.As highlighted in previous studies, both varietal and genetic diversity were spatially structured among major agricultural production areas, as well as several of their portential drivers describing cropping systems, pathogen pressures and institutional determinants of the formal wheat sector. We hypothesized that these potential drivers could have a higher explanatory power of the varietal diversity (based only on the varietal denomination summarizing performances of the variety on which farmers rely to make their varietal choices). Based on a set of fine-grained spatio-temporal datasets, we computed indicators considered as relevant proxies of these portential drivers and conducted a set of statistical analyses and an expert survey. We confirmed that the drivers identified explained more the spatio-temporal structure of bread heat varietalrather than genetic diversity. In addition, these results highlighted that diversity appeared to be higher when larger production areas of bread wheat with a greater diversity of preceding crops were sown, then potentially promoting the choice of a higher number of varieties with different earliness classes. On the contrary, a high proportion of maize or wheat as preceding crops, know to have adverse effects on subsequent wheat production, as well as a high level of risk of pathogens favored by these preceding crops, such as fusarium head blight, were negatively correlated with a higher varietal diversity. A higher production area of bread wheat with greater diversity of preceding crops was also positively associated with a higher neutral genetic diversity, hile more specialized agroecosystems would reduce the effective and relevant varietal choice.