Objectives Turner syndrome (TS) is a complex and chronic medical condition that requires lifelong subspecialty care. Effective transition preparation is needed for successful transfer from pediatric to adult care in order to avoid lapses in medical care, explore health issues such as fertility, and prepare caregivers as adolescents take over responsibility for their own care. The objective of this study was to evaluate accuracy of knowledge of personal medical history and screening guidelines in adolescents and young adults (AYA) with TS. Methods This was a prospective cross-sectional study of 35 AYA with TS of ages 13–22 years recruited from a tertiary care center. AYA completed questionnaires on personal medical history, knowledge of screening guidelines for TS, and the Transition Readiness Assessment Questionnaire (TRAQ). Results Eighty percent of AYA with TS were 100% accurate in reporting their personal medical history. Only one-third of AYA with TS were accurate about knowing screening guidelines for individuals with TS. Accuracy about knowing screening guidelines was significantly associated with TRAQ sum scores (r = 0.45, p < 0.05). However, there was no association between knowledge of personal medical history and TRAQ sum scores. Conclusions Transition readiness skills, TS-specific knowledge, and accurate awareness of health-care recommendations are related, yet distinct, constructs. Understanding of one’s personal medical history is not an adequate surrogate for transition readiness. Validated tools for general transition, like the TRAQ, can be used but need to be complemented by TS-specific assessments and content. Providers are encouraged to identify opportunities for clinical and educational interventions well in advance of starting transfer to adult care.