Students with Disabilities (SWD) are underperforming in reading when compared to their neurotypical peers. Although reading research has made significant progress over the past 30 years, including recent developments regarding the science of reading, the findings from the extensive body of research are not consistently grounding instructional decisions. Research clearly emphasizes the need to use evidence-based practices to improve reading outcomes for SWDs. However, secondary level special education teachers lack training in implementing such practices. Research indicates that professional development (PD) as part of any educational reform efforts must be grounded in the understanding that change begins with the learning of educational professionals and that only through increasing adult learning will we ultimately increase student learning. This mixed methods study relied on elements of improvement science to gain a deeper understanding and investigate if a multi-tier professional development (PD) intervention would increase teacher collaboration, teacher knowledge, teacher practice, and improve reading outcomes for SWDs. The three primary drivers were: (a) develop Specific, Measurable, Achievable, Relevant, and Time-Bound (SMART) goal writing and progress monitoring, (b) increase opportunities for teacher collaboration and (c) strengthening knowledge and practice in quality teaching. The three PDSA (Plan, Do, Study, Act) cycles implemented as part of the intervention included: (a) Restructured Department Meetings, (b) Lunch [and] Learns, and (C) Reading Pilot PLC. Multiple data points were collected including surveys, exit tickets, Kiva Protocol, student data, IEP analysis, and teacher interviews. Findings indicate increased collaboration among teachers, increased teacher knowledge regarding reading, SMART goal writing and progress monitoring as well as statistically significant reading growth for SWD. [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.]