This article explores several dioceses in Tuscany—Arezzo, Fiesole, Lucca, Montepulciano, Siena, and Volterra—in light of the foundation of diocesan seminaries, to determine if a new corps of priests was produced and if that corps instituted major changes. Historians refer to post-Tridentine attempts to strengthen the faith and power of groups and institutions by such processes as education as the parallel trends of confessionalism and confessionalization. Since these dioceses represent different economic, educational, and demographic levels of development, the comparative study of quantitative and qualitative measures in these regions addresses the impact of educational changes in the parish clergy in a significant cross-section of late-sixteenth and seventeenth-century Tuscany. Even in dioceses which were wealthy and which supported seminaries, the institutions had little influence, and therefore the slow and spotty improvements in the parishes and dioceses did not result in the confessionalization of the region, although limited confessionalism did occur.