The study aimed to determine the differentiated instruction (DI) and teaching proficiency

of secondary mathematics teachers in Eastern Samar Division. Using descriptive-comparative and

correlational research designs, data gathered using a survey questionnaire from 207 secondary math

teachers and 59 immediate supervisors. Mann-Whitney U Test and Kruskal-Wallis Test for

comparison and Spearman Rank Correlation Coefficient for testing the relationship between

variables were used at 5% level of significance. The study revealed that most of the respondents

were female, in the adulthood stage, with units in masters, holding Teacher I position, specializing

mathematics, novice teachers, and attended a minimal number of DI training/seminars. The

respondents displayed a “highly practiced” DI and “outstanding” level of teaching proficiency.

Likewise, results showed no significant differences in the respondents’ level of DI and teaching

proficiency when grouped by sex, age, educational attainment, teaching position, specialization,

teaching experience, and training/seminars attended related to DI. Lastly, the level of DI was found

to explain variation in the level of teaching proficiency. The study recommends real-time

professional development on DI, where respondents will be equipped with relevant and updated

concepts and where they can share and showcase their experiences and best practices in teaching

mathematics.