This series of three studies identified an experimental research gap in the field of deafblindness. Study 1, a descriptive study, identified types of articles published, and research designs used, in 37 peer-reviewed special education journals. A total of 4,854 articles published from 2012 through 2017 were examined to determine types of articles and research methods informing policy and practice during the 6-year period and contributing to identification of future research needs. Similar numbers of qualitative designs, single case research designs, and other quantitative designs were implemented with IDEA-eligible individuals identified as deafblind (DB). Fewer than half of these studies identified were intervention studies. a limited number of intervention studies was identified in special education publications. Study 2 was a census of state deafblind project technical assistance providers. The survey was sent to 151 potential respondents with a return rate of 45% to find out what instructional methods were used or taught to others, if systematic response prompting, specifically the system of least prompts, was used, and reported proficiency in implementation of the SLP. Only one TA provider accurately answered all questions about implementation of components of the SLP, but 46% reported providing TA to increase use of response prompting methods. TA providers listed limited alternative instructional methods to response prompting. In Study 3, the experimental research gap was addressed through an evaluation of the system of least prompts to teach symbol use to three children with deafblindness. A multiple probe design across three symbols and replicated across participants was used to teach symbols for manding preferred activities. Overall, there were mixed results. Two participants increased symbol use across all symbols. The third increased use of one symbol. [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.]