The use of educational technology in K-12 classrooms has been gaining tremendous momentum across the country since the 1990s. Many school districts have been investing heavily in various types of technology, such as computers, mobile devices, internet access, and interactive whiteboards. Almost all public schools have access to the internet and computers in their schools. Educational digital games have also been growing significantly in the past few years. To support the use of educational technology, the U.S. Department of Education provides grants to state education agencies. For example, in fiscal year 2009, the Congress allocated $650 million in educational technology through the Enhancing Education Through Technology (E2T2) program (SETDA, 2010). Given the importance of educational technology, it is the intent of this review to examine the effectiveness of various types of educational technology applications for enhancing mathematics achievement in K-12 classrooms. This review employed meta-analytic techniques proposed by Glass, McGaw & Smith (Glass, McGaw, & Smith, 1981) and Lipsey & Wilson (2001). This review indicates that incorporating supplemental programs into regular classroom curriculum may be beneficial (Eisenberg & Johnson, 1996; C. L. C. Kulik & Kulik, 1991), and adhering to program usage guidelines suggested by technology providers may be helpful in improving student achievement. (Contains 15 tables.)