Effects of Online Professional Development on Teachers’ Instructional Reading Adaptations for English Learners through Data-Based Individualization

English learners (ELs) make up a significant portion of the nation’s K-12 student population who come from culturally and linguistically diverse backgrounds. ELs bring a wealth of diversity to the United States’ education system; however, teachers’ limited knowledge and practices of how to integrate ELs’ cultural, linguistic, and prior educational experiences in the general education curriculum can contribute to low academic growth and overidentification into special education programs, particularly for learning disabilities in reading. This study examined the impact of online professional development on general and special education teachers’ knowledge of data-based individualization (DBI) and curriculum-based measurement (CBM) to adapt validated reading interventions with culturally and linguistically responsive practices (CLRPs) for ELs with persistent reading difficulties. Results indicated very large effect sizes of online DBI/CBM + CLRP professional development on teacher knowledge; however, a functional relation could not be determined due to the study ending before all teachers finished the professional development components. The findings of this study provide several implications for online DBI professional development and adapting validated reading interventions for ELs. Suggestions for future research are also offered.