The change in pH during Cheddar cheese-making is largely determined by the buffering capacity of milk, curd and/or whey, and is moderated by the presence of inhibitors and treatment of milk prior to cheese-making. The pH change kinetics during Cheddar cheese-making starting from raw, heat-treated, micro-filtered (MF), and high-pressure (HP)-treated milks were evaluated. Heat treatment and micro-filtration were equivalent of achieving commercial pasteurization of milk. High-pressure treatment included two pressure levels and two treatment times (300 MPa for 60 and 90 min and 400 MPa for 32 and 40 min), calculated to be equivalent to achieve 4 and 6 decimal reductions of Listeria monocytogenes counts. Kinetics of pH change were evaluated during three stages of the Cheddar cheese-making process—milk ripening, cooking/holding and cheddaring. The influences of different treatments on pH change were somewhat different in the three phases studied. The pH decreased linearly with time during the first two stages and decreased logarithmically with time in the cheddaring phase. As compared to the ripening of untreated raw milk, all other treatments retarded the rate of change in pH with the micro-filtration having the lowest rate. During the cooking/holding stage, pasteurized and MF milks slightly enhanced the rate of pH change, while HP-treated milks continued the slower rate. During the final stage (cheddaring), the rate of change in pH with the HP-treated milks was about the same as in MF milk; however, both delayed the rate relative to raw and heat-pasteurized milks.