This research study examined the effects of hybrid course format as compared to face-to-face instruction format in a high school setting. At this time, there is little research on hybrid courses in the secondary schools. The quantitative portion of this ex post facto study utilized causal comparative design. Student data was collected from teacher created assessments as well as the student information system. To collect qualitative data teachers were asked a series of questions about the hybrid teaching experience. The Blended Course Faculty Survey created by the University of Central Florida and the American Association of State Colleges and Universities was utilized for the interviews (University of Central Florida (UCF) and the American Association of State Colleges and Universities (AASCU), 2011). The research questions include: 1) What is the difference in knowledge gained as measured by the teacher created assessment based on course format, (hybrid or traditional)? 2) What is the difference in student attendance based on course format? 3) What is the difference in knowledge gained due to gender? 4) What are the high school teachers' perceptions of the effectiveness of hybrid learning? When examining achievement both the hybrid and traditional courses showed a significant increase in assessment scores. This increase did not hold true for the students enrolled in the traditional Psychology course. The attendance data showed students in hybrid courses missed an average of 2.02 classes while those in the traditional course missed an average of 4.38 classes. Psychology was the only course that did not show a significant difference between the number of absences for hybrid and traditional students. The examination of gender showed both males and females demonstrated significant increase in assessment scores overall. The exception was found for males who attended the Psychology course. The qualitative information from the teacher interviews showed varying opinions on the many facets involved with hybrid courses. Overall, two teachers would teach a hybrid course again and have taken some of the hybrid components and added them to their traditional courses. A third teacher was not satisfied with the experience and felt the need to physically interact with students every day. Recommendations for further implications and future research were discussed. [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://www.proquest.com/en-US/products/dissertations/individuals.shtml.]