The effectiveness of the Chicago Mastery Learning Reading (CMLR) Program implemented in Ontario's Kettleby Public Schools (KPS) was measured by the students' reading progress and comparisons with the progress of other students in French immersion (FI) and other non-FI programs, including a gifted program. Within six months of CMLR implementation, a test of reading comprehension found the KPS students with slightly higher mean average scores than their non-FI peers and significantly higher scores than their FI peers. A year later, a test of literal comprehension resulted in lower scores for the KPS group than for others, but the difference was marginal when gifted student scores were factored out. Another six months later, a more comprehensive reading test of factual comprehension, inference, and generalization skills resulted in KPS scores equal to the scores of non-FI students when gifted scores were factored out. Item analysis and skills analysis identified apparent strengths and weaknesses of the KPS performance in comparison to other groups, and resulted in recommendations for action. (Author/MSE)