The adoption of the new DepEd K-12 Basic Education Curriculum entails using mother tongue-based (MTB) instruction and content in all the subjects from Grades 1 to 3, which includes the beginning content of Science in Grade 3. The study focused on the development, evaluation, and validation of a Kapampangan Teacher's Guide (KTG) in Science 3. In this study, the KTG is the Translated Language (TL) material developed after the translation and contextualization of the Source Language (SL) - the English Teaching Guide (ETG). The development of KTG aimed to provide teachers the needed instructional material in teaching Science 3 vis-a-vis the use of a Kapampangan Learners Material (KLM) that applies to either the face-to-face or the distance learning form of modality. Descriptive-developmental research design was applied to obtain the numerical data deduced from the evaluation and validation tools administered. Purposive or selective sampling technique was employed in determining the efficiency of the material. The findings of the study used the mode as a measure of central tendency, revealing that 22 of the criteria evaluated were rated "Excellent" by five (5) Science and five (5) Mother Tongue Based (MTB) teachers. The criteria evaluated are the objectives, content and organization, manner of presentation and layout, and the degree of usefulness of the KTG. Whereas, seven (7) criteria out of nine (9) language considerations in the KTG validated were rated "Strongly Agree" by a group of five (5) language experts. With the result of the evaluation and validation, the KTG in Science 3 is categorically functional and purposeful in providing teachers another guide in teaching Science 3 that is contextualized after the learners' Kapampangan language. Keywords: Kapampdngan Teacher's Guide, development, evaluation, validation, Science 3.