Since the introduction of the specific learning disability (SLD) classification in federal special education legislation, there has been considerable ambiguity and controversy about the criteria that should be used in the determination of SLD (Kavale & Flanagan, 2007; Zumeta et al., 2014). Various models have been introduced to identify students who qualify for services under the SLD category, but the literature suggests the determination of SLD varies widely from state to state, district to district, and evaluator to evaluator (Cottrell & Barrett, 2016; Maki et al., 2015; Reschly & Hosp, 2004). Given the ambiguity of SLD regulations in states like Massachusetts, the purpose of this study was to investigate trends in the clinical reasoning of school psychologists when making an SLD determination, particularly when faced with a difficult or equivocal case. Thirteen school psychologists from public elementary schools in Massachusetts participated in semi-structured virtual and face-to-face interviews. Analysis of qualitative data using grounded theory (Saldana, 2009) produced the following major themes: 1) use of SLD models, 2) reliance on team and data-based decision making, 3) reality of ethical dilemmas, and 4) importance and benefits of consultation. Results of the study found that most Massachusetts school psychologist participants used a combination of existing SLD models and relied on multiple data points in making a determination with the main goal of ensuring special education supports for the student. Although many participants considered data from RTI interventions, criteria for adequate progress under RTI were seen as vague. When using a discrepancy model, most participants cited a 1.5 standard deviation gap between ability and achievement as the basis for determination. Some participants also described considering general patterns of strength and weaknesses but did not use a specific PSW method. Participants generally reported a team approach to decision-making, but school psychologists were typically seen as gatekeepers for SLD determination whereas special educators were the gatekeepers for setting special education goals. Participants described various ethical challenges faced in making a determination and often relied on consultation to help with decision making. Among the clinical implications suggested by the results is the need for increased clarity and criteria for adequate progress in the data collected from RTI interventions. Results also suggested that exclusionary criteria, particularly English as a second language, are confounding factors in making an SLD determination and should be reconsidered. Finally, increased use of group supervision and professional learning communities for school psychologists were strongly recommended to improve and support decision making, particularly in eligibility determination for complicated cases. [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.]