This mixed-methods research study was designed to investigate the effect of learning styles on the academic achievement of at-risk high school students in a blended learning environment. The researcher analyzed students' academic achievement scores and students' learning styles. The researcher used Kolb's learning style inventory 4.0 to assess students' learning styles. In addition, instructional strategies data from teachers were collected to assess the effect on academic achievement when instructional strategies match learning styles. For analysis, the researcher determined a degree of match score for instructional strategies matched to learning styles. -- Statistical analysis of the data revealed that there was no significant relationship between learning styles and academic achievement. The researcher determined there was no relationship between the degree of match scores and the content areas English language arts, mathematics, and science. A Spearman's rank order correlation test revealed a significant relationship between degree of match scores and achievement only in the content area of social studies. Qualitative analysis revealed that when there was alignment between the learning environment, instructor type, and the learning style, students achieved at higher levels than when there was no alignment. -- This research suggests that teachers should be aware of the learning styles of their students and provide various instructional strategies to ensure the success of all students. There is also evidence in this research to suggest that accommodating learning styles has a positive influence on academic achievement. It is recommended that instructors work with students to increase their flexibility in learning situations. This research suggests that teaching to a variety of learning styles may be more beneficial than simply matching student preferences alone.