Objective: The goal of this study was to determine core competencies by means of a systematic literature review and to design and test an interpreter training program. Methods: Core competencies in medical interpreting were searched using a systematic literature review. An intervention program was developed to improve core competencies. Pretests and posttests were conducted to pilot-test knowledge and interpreting skills in participants aged 22-62 years (n = 43). Results of the tests were compared. Results: Results of the systematic review indicated five core competencies: (a) maintaining accuracy and completeness; (b) medical terminology and understanding the human body; (c) behaving ethically and making ethical decisions; (d) nonverbal communication skills; and (e) cross-cultural communication skills. Statistical analysis showed a significant improvement in knowledge and interpreting skills in the intervention program compared with the control program. Conclusion: Posttest assessment showed that the developed training system can be useful in improving knowledge and quality in medical interpreting. Practice implications: A 3-day training program for medical interpreters could bridge the gap between medical professionals and patients with limited English proficiency while being amenable to integration into clinical flow. (C) 2013 Elsevier Ireland Ltd. All rights reserved.