This study aims to design mathematical literacy instruments that have evidence of content and construct validity and are reliable for use as an assessment for learning. The research involved eight experts as instrument validators and 273 eighth-grade students of junior high school in Yogyakarta Province. The results showed that the ten mathematical literacy items developed had the V Aiken coefficient index calculated from 0.781 to 0.906 (> 0.75). The results of adequacy testing of samples with KMO and Bartlett show Chi-Square in the Bartlett test of 608,608, the p-value <0.05 and KMO value of 0.781 (> 0.5). The results of testing of the measurement model with Confirmatory Factor Analysis (CFA) produce a Root Mean Square Error of Approach (RMSEA) value of 0.049 ([less than or equal to] 0.08), chi-s Square of 33.92 (<2df), the p-value of 0.05004 ([greater then or equal to] 0.05). Nine out of the ten items developed had t-value> 1.96, Standardized Loading Factor (SLF) was greater than the critical limit (> 0.3), and Construct Reliability (CR) of 0.78 (> 0.7). It can be concluded that the developed mathematical literacy instrument can measure what must be measured and nine items significantly reflect the construct or latent variable, as well as the level of consistency of a good score.