Assessment literacy is currently gaining attention because of its relevance to teachers' instructional practices and students' performance. Previous studies showed that Filipino teachers have low to mid-level assessment literacy. Therefore, it is crucial to determine how teachers view their assessment literacy. This study aimed to develop and determine the validity and reliability of the Self-Reported Assessment Literacy Instrument. Five experts on science education validated the instrument. After revising it based on the validators' comments and suggestions, it was pilot-tested on 42 science teachers. After a series of minor revisions based on the pilot results, the instrument was administered to 107 teachers. The exploratory factor analysis of the results revealed that it almost followed the three-dimensional model of assessment literacy. The findings also showed that the instrument is reliable and valid for surveying self-perceived assessment literacy. Therefore, it is recommended for use in measuring self-reported assessment literacy.