The use of technology in education has grown rapidly over the past few decades resulting in the adoption of 1:1 device initiatives in numerous schools and districts. As with any school-based initiative, teachers play an integral role. The effectiveness of an initiative is often measured in terms of student achievement to which teachers are directly linked. However, a variance of proficiency utilizing technology is common amongst teachers (Dogan & Akbarov, 2016), which may impact the efficacy of a 1:1 device initiative. The purpose of this mixed methods study was to identify teachers' perceptions regarding both, a 1:1 device initiative in general, and the professional development practices provided for its implementation. Some of the advantages and challenges inherent within a 1:1 device initiative were identified, as were teachers' perceptions regarding the effects on the following: knowledge and understanding of content and instructional practices, classroom practices, efficacy as a teacher, and student achievement. This study's target population was secondary teachers in southeastern Pennsylvania and data was collected using a survey and follow-up interview. In identifying and understanding teachers' perceptions regarding the professional development practices provided, school leaders may be better able to select and implement effective practices specifically for the implementation of a 1:1 device initiative. The results of this study indicate that teachers, working within a 1:1 device initiative, prefer professional development that is differentiated to meet their individual needs. A common theme emerged indicating that while teachers believe a 1:1 device initiative has made many aspects of teaching "easier", there is a clear need for more professional development. Teachers consistently expressed a desire to collaborate and discuss various strategies with fellow teachers before implementation in the classroom. Until that is realized, positive effects on student achievement may not be fully realized. [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.bibliotheek.ehb.be/en-US/products/dissertations/individuals.shtml.]