The purpose of this research study was four-fold: (1) to determine to what extent educational diagnosticians possess knowledge of Cattell-Horn-Carroll (CHC) theory of cognitive ability and its relationship to academic learning, (2) to determine to what extent educational diagnosticians recommend possible evidence-based instructional interventions based on CHC theory, (3) to determine to what extent educational diagnosticians recommend accommodations based on CHC theory, and (4) to determine educational diagnosticians' perceptions regarding their training and/or preparation programs and knowledge on how to recommend possible instructional interventions and accommodations based on the relationship between cognitive ability and academic learning as presented in Cattell-Horn-Carroll (CHC) theory. The study used mixed methodology organized into two phases. Whereas the first quantitative phase utilized survey research, the second qualitative phase utilized focus group research.

The quantitative phase used an online survey for data collection to determine the validity of significant variables generated in survey research. Participants were educational diagnosticians who were all on the Texas registry of professional educational diagnosticians. The survey was completed by 42 participants. A Likert scale instrumentation rated acquired skills for linking the relationship of CHC cognitive ability and academic learning on a 1–5 point scale rating from "low to high", and extent of recommending instructional interventions and accommodations on a 1–5 point scale rating from "never" to "always". Responses from the survey were analyzed using descriptive statistics and a cross tabulation X² test.

The qualitative phase clarified how educational diagnosticians acquired knowledge of linking the relationship of cognitive ability factors to academic learning and their recommendations of instructional interventions and accommodations in the form of a focus group utilizing Metaplan procedures. Five professional educational diagnosticians participated in the focus group.

Results of the study indicated that most educational diagnosticians reported having knowledge of the relationship between CHC theory of cognitive ability factors and academic learning. They also reported that most of them recommend instructional interventions and accommodations based on this knowledge.

The results also specified that most educational diagnosticians receive quality training programs related to the relationship between cognitive ability and academic learning as presented in Cattell-Horn-Carroll (CHC) Theory. However, they reported the need for better formal preparation in linking cognitive ability factors to academic learning. In addition, participants ranked application and communication as the most important barriers when linking CHC theory to academic learning.