PURPOSE: To develop and test the validity of a surgical competency assessment tool for simulated small-incision cataract surgery (SICS). SETTING: Participating ophthalmologists contributed from 8 countries. DESIGN: Qualitative and quantitative development and evaluation of face and content validity of an assessment rubric, and evaluation of construct validity and reliability. METHODS: The SICS Ophthalmic Simulated Surgical Competency Assessment Rubric (Sim-OSSCAR) was developed and assessed for face and content validity by an international group of experienced ophthalmologists. Groups of novice and competent surgeons from 4 countries were recorded performing surgery, and masked assessments were performed by 4 expert surgeons, to determine construct validity and reliability. RESULTS: The Sim-OSSCAR for SICS was assessed by a panel of 12 international experts from 8 countries. In response to the question, "Do you think the OSSCAR represents the surgical techniques and skills upon which trainees should be assessed?," all respondents either agreed or strongly agreed. Face validity was rated as 4.60 (out of 5.0). The content was iteratively agreed to by the panel of experts; final content validity was rated as 4.5. Interobserver reliability was assessed, and 17 of 20 items in the assessment matrix had a Krippendorff α correlation of more than 0.6. A Wilcoxon rank-sum test showed that competent surgeons perform better than novices (P = .02). CONCLUSIONS: This newly developed and validated assessment tool for simulation SICS, based on the International Council of Ophthalmology's Ophthalmology Surgical Competency Assessment Rubric, has good face and content validity. It can play a role in ophthalmic surgical education.