Training of standardized patients (SPs) for national high-stakes OSCE helps to ensure a reliable assessment of student performance in various clinical scenarios. However, workflow protocols to train SPs vary. Medical schools adopt specific measures to ensure standardization. We present a development workflow of the SPs' training framework for high-stakes OSCE using a volunteer SPs' bank. Our approach was guided by the social learning theory. Three educators and 17/20 (85%) members of our volunteer SPs' bank worked in a collaborative partnership on the construction of pedagogical content of the training framework comprising three 2-hour sessions. Since SPs have to demonstrate acquired behaviors, intended learning outcomes used the words "apply", "perform" and "participate." A principal part of the evaluation was the achievement of intended learning outcomes by the SPs during 3 formative OSCEs. Seventeen SPs, 356 fourth year medical students and 60 examiners participated. Quantitative and qualitative data were collected by post-session questionnaires and analyzed using descriptive statistics and thematic analysis. Twelve examiners evaluated a mean of 29.7+/-0.14 SD patient-student encounters. In total, 15/16 SPs (93.8%) considered the contact with students as easy and 4 SPs (31%) reported the experience as stressful. Two themes emerged from the free-text comments: "Gaining experience as SP" and "Concerns for evaluated students." The proposed SPs' training framework for high-stakes OSCE may be useful for other medical disciplines and health professions initiating SP-based assessment programs. The strategy of development and evaluation are outlined to guide a successful application of the curriculum standards.