Background: Missed appointments without cancellation or no shows can cause disruptions in necessary healthcare services, which can be potentially detrimental for persons with chronic health conditions such as multiple sclerosis (MS). While persons with MS (PwMS) can face several barriers to receiving healthcare services, such as mobility and accessibility, little is known about the contributing behavioral factors, which may serve as targets for an intervention to reduce missed appointments. Objectives: To identify whether certain behavioral targets (objective and subjective cognition, self-efficacy, and personality traits) were predictive of missed MS-related appointments. Methods: Participants (n = 110) were PwMS who received their MS-related care at the Mandell Center and completed the Memory for Intentions Test (MIST), Symbol Digits Modalities Test, Rey Auditory Verbal Learning Test, Perceived Deficits Questionnaire (PDQ), University of Washington Self-Efficacy Scale, and NEO Five Factor Inventory-3 (NEO FFI-3) as part of a self-management study. To limit the impact of COVID-19 on the attendance data, only participants who were evaluated between June 2019 and early March 2020 were included in the analyses. Appointment attendance data were extracted from the electronic medical record and were limited to MS-related appointments for the year prior to the study assessment. Logistic regressions were conducted, with 1+ no shows as the outcome, with age, disease modifying therapy usage, race, socioeconomic status, number of comorbidities, and distance from the Center as covariates. Results: Twenty percent of participants had at least one missed MS-related appointment in the previous year. Prospective memory was a significant factor in having a no show, including both subjective (PDQ subscale: b = 0.18, p = .041) and objective measures (MIST total: b = -0.02, p = .023). In addition, impairment on the fourth task of the MIST, which we identified in a separate analysis as being sensitive and specific to overall prospective memory deficits, was a predictor, with an adjusted odds ratio of 5.45 (p = .013). Finally, high to very high levels of neuroticism on the NEO-FFI-3 predicted 1+ no shows, with an adjusted odds ratio of 3.86 (p = .023). Conclusions: Difficulty remembering to remember and higher levels of neuroticism are associated with missed MS-related appointments. The next steps will be to evaluate whether behavioral interventions that target these areas result in improved appointment attendance.