Adaptive/therapeutic riding (AR/TR) comprises horseback riding lessons that are adapted to be safe and effective for individuals with disabilities. Instructors' knowledge of equine behavior and learning theory is an important consideration in maximizing human safety and equine welfare in AR/TR lessons. Yet, little is known about AR/TR instructors and their knowledge of horse behavior and learning theory. The purpose of this study was to characterize AR/TR instructors, their experience with horses, and knowledge of horse behavior and learning theory. An online survey was distributed to AR/TR instructors and instructors in training through the Professional Association of Therapeutic Horsemanship, International. Two-hundred four complete responses were retained for data analysis. Summary statistics (counts, percentages, means, medians, interquartile ranges, ranges) were calculated for multiple choice, Likert-scale, and short answer questions (SAS (R) v9.4). Reponses to open-ended questions were coded using deductive and inductive content analysis (Nvivo (R) v1.7.1). Logistic regression was used to analyze the relationship between experience and correctly identified behavioral profiles and operant conditioning definitions and scenarios (SAS (R) v9.4). Most respondents were white (98 %), female (97 %), certified therapeutic riding instructors (74 %) with a mean age of 50 years. Fourteen years was their mean of AR/TR instructor experience. Prior horse experience was reported as mean of 20 years of recreational or 12 years of professional experience. Only 5 % correctly identified all horses' behavioral profiles in video clips. Twenty-two and 21 % of respondents correctly identified all operant conditioning definitions and scenarios, respectively. Age of the respondent decreased the odds (odds ratio (OR) 0.984, p < 0.0001) of correctly answering the behavioral profile questions whereas years experience as an AR/TR instructor or instructor in training increased the odds (OR 1.020, p = 0.0026) of correctly answering the behavioral profile questions. Respondents' experience in equine-assisted services prior to becoming an instructor or instructor in training (years), age, and hours spent teaching AR/TR lessons per week decreased the odds (OR 0.980; 0.987; 0.979, p <= 0.0198) of correctly identifying the operant conditioning definitions. Respondents' prior EAS and horse experience and hours spent teaching AR/TR lessons decreased the odds (OR 0.982; 0.988; 0.980, p <= 0.0246) of correctly identifying the operant conditioning scenarios. Results show experienced instructors were more likely to correctly identify horses' behavioral profiles, but less likely to correctly identify operant conditioning. Overall, these results highlight the need for continuing education for AR/TR instructors on horse behavior and learning theory to address the documented low knowledge levels.