Over the past ten years, districts have made large purchases of instructional technology for use in the classroom. In particular, many districts are purchasing one device per one student, otherwise known as one-to-one initiatives (Dorfman, 2016). The costs of these initiatives are great and because of this, communities are demanding they be integrated into the curriculum (Dunleavy, Dexter, & Heinecke, 2007; Hayes & Greaves, 2013). There are multiple barriers to successful integration of instructional technology (Ertmer, 1999). To overcome these barriers and beliefs, teachers need professional development in a variety of forms: formal, informal, and independent (Jones & Dexter, 2014). Additionally, educational leaders, particularly principals, need to take an active role through their leadership actions in making certain teachers receive the professional development they need as well as to support technology integration actions in the classroom (Chang, 2012). The purpose of this study is to examine the relationship between formal, informal, and independent instructional technology professional development offerings, the leadership actions of Principals and teacher biases and barriers, and their influence on public middle school teachers' integration of instructional technology in a one-to-one environment. This quantitative study utilized cluster sampling of 12 Long Island, New York middle schools with at least one grade having an established one-to-one initiative. From these schools and grades, 1040 teachers were surveyed concerning the leadership actions of their principals in relation to professional development and instructional technology integration, teachers' beliefs about, and barriers to, instructional technology integration, and how they integrated instructional technology after participating in each of the three forms of professional development. The findings from this research indicate that principals need to take a more active role, through their actions, to both encourage teacher participation in formal, informal, and independent professional development, and promote instructional technology integration. Letting teachers know they will be evaluated on instructional technology integration was found to be effective for integration. Additionally, teachers continue to use formal professional development to help them integrate instructional technology more than informal and independent professional development. Finally, teachers continue to report time as a belief and barrier to instructional technology integration far more than any other barrier in these one-to-one classrooms. [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://bibliotheek.ehb.be:2222/en-US/products/dissertations/individuals.shtml.]