The purpose of this mixed method descriptive study was to investigate the relationship between deaf educators' perceived efficacy of a specifically-designed curriculum and DHH learners' use and comprehension of function words in written text, and explore unknown perceptions related to the research topic. The study was conducted to address gaps in the literature regarding DHH learners' development of function words. The independent variable was the specifically-designed function word curriculum (FWC) and the dependent variables were DHH learners' use and comprehension of function words in written text. Pearson r correlation coefficients, ANOVAs, and descriptive statistics were used to analyze the results of the study. The theories of social-cognitive, socio-cultural, and information processing were the foundations for the study. The data indicated that a relationship existed between deaf educators' perceived efficacy of the FWC and DHH learners' use and comprehension of function words in written text. The null hypothesis for RQ1 and RQ2 were rejected. The qualitative data corroborated quantitative findings. A representative sample was obtained sufficient to generalize findings across the population. The current study highlights the importance of function word development for DHH learners. Results of the study add to the literature on DHH vocabulary development and provide considerations for future research. Future research is recommended to explore the ways in which practitioner beliefs align with research-based practice and the effect on DHH learner outcomes. [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.]