The demand for online instruction in high schools across the nation continues to rise with each year prompting the development of new on-line programs and courses. Online instruction on one hand is believed to increase the accessibility of educational opportunities for students who would otherwise not attend school for several reasons as well as give students an opportunity to increase their marketability through use of up-to-date technology. On the other hand, some believe that the human interaction between the instructor and the students and the interaction amongst students which are critical parts of an educational process are minimal or almost non-existent, therefore, lowering academic standards. This paper discusses the relative effectiveness of on-line instruction in high schools and its implications on students’ academic achievement.