This thesis evaluates the curricula implemented in four mother-tongue based multilingual education programs in the Philippines, Thailand, East Timor, and Cameroon. The method for conducting research in this thesis is based on the five principles to enhance learning presented by the World Bank and the prism model developed by Thomas and Collier. The five principles presented by the World Bank are as follows: (1) Teach children in a language they understand starting with Early Childhood Education and Care services through at least the first six years of primary schooling, (2) Use a language children understand for instruction in academic subjects beyond reading and writing, (3) Introduce an additional language (if desired) as a foreign language with a focus on oral language skills, (4) Continue using the language children understand for instruction even after a foreign language becomes the principal language of instruction, (5) Continuously plan, develop, adapt, and improve the implementation of language of instruction policies, in line with country contexts and goals. The prism model developed by Thomas and Collier illustrates the four most influential factors of student success in MTB-MLE programs: language development, academic development, cognitive development, and sociocultural processes. When MTB-MLE programs in low and middle-income countries apply the prism model developed by Thomas and Collier and follow the five principles presented by the World Bank, they can and do improve the achievement of language minority students. This research provides evidence that the first five recommended best practices can be used as standard determiners of curriculum quality regardless of geographic location or family incomes. Evidence was found for seven effective innovative practices: (1) extending MTB-MLE program duration through sixth grade, (2) using daily calendar activities as part of math and language instruction, (3) using integrated readers that include academic content in reading instruction, (4) teacher training when school is not in session, (5) including preschool programs in L1, (6) inviting parents to school, and (7) writing about recent life experiences with close family members as a way to promote creative writing. [The dissertation citations contained here are published with the permission of ProQuest LLC. Further reproduction is prohibited without permission. Copies of dissertations may be obtained by Telephone (800) 1-800-521-0600. Web page: http://bibliotheek.ehb.be:2222/en-US/products/dissertations/individuals.shtml.]