This book constitutes the refereed proceedings of the 12th International Conference on Blended Learning, ICBL 2019, held in Hradec Kralove, Czech Republic, in July 2019. The 28 papers presented were carefully reviewed and selected from 80 submissions. The papers are organized in topical sections named: personalized and adaptive learning; content development for blended learning; experience in blended learning; analytics and evaluation for blended learning; open educational resources; and pedagogical and psychological issues.