The high school (HS) graduation rate of students with disabilities who have individual education programs (IEP) is historically low compared with their non-disabled peers. The problem was that a statewide initiative to improve the standard HS diploma graduation rate of students with disabilities, the April Dunn Act (the Act), was perceived as being inconsistently implemented and its results were not well understood. The purpose of this multi-modal qualitative case study was to explore how teachers were implementing the Act and to better understand how the graduation rates for these students trended before and after the Act's implementation. The conceptual framework included intervention theory combined with the state's rules and requirements for the Act's implementation and maintenance. Publicly available archival graduation data were examined to answer the first research question related to how the graduation rates for students with disabilities and IEPs trended before and after the implementation of the Act. Overall, the graduation rates for these students trended up sharply 4 years after the Act's implementation. The second research question to explore how teachers perceived the implementation of the Act employed a purposive sample of 10 HS special education teachers. Thematic data analysis resulted in 8 themes related to (a) adequate training, (b) statewide assessment data, (c) community effort, (d) awarding HS credit, (e) continuous evaluation for newly eligible students, (f) progress monitoring, (g) intervention complexity, and (h) improved retention. Positive social change results when more students with disabilities earn a standard high school diploma because high school graduation provides a critical pathway to increased economic success and life satisfaction. [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.]