Materials based on BiMO₃-modified BaTiO₃ have been shown to exhibit a number of attractive electrical and electromechanical properties. In addition, many of the materials in this broad family exhibit reduced sintering temperatures for densification as compared to pure BaTiO₃. We report here a study of the phase evolution and sintering behavior of Bi(Zn_1/2Ti_1/2)O₃-modified BaTiO₃ materials from low-cost mixed oxide/carbonate precursor powders. By accelerating the reaction of the BaCO₃ species and increasing the diffusion kinetics associated with densification, Bi(Zn_1/2Ti_1/2)O₃ additions reduce the calcination and sintering temperatures by ~200°C compared to unmodified BaTiO₃. This system provides an example of the important and often overlooked role of additives in the calcination, phase evolution, and densification processes, and provides insight into mechanisms that may be further exploited in this and other important materials systems. We are quite honored to have the opportunity to publish in a special issue dedicated to the life and work of our dear late colleague Prof. Marija Kosec. The topic of this paper is fitting as well, since the work was in large part directly inspired by her work on the importance of reactions and intermediate phases in the alkali niobate systems and heavily informed by her work on the Pb-based perovskites. Marija appreciated better than most the importance of careful processing in the formation of fine ceramics, and the global ceramics community is grateful to her for all of the lessons that she taught us—and through her papers and her students, continues to teach us.