Self-proficiency, distinct from self-efficacy, is a more comprehensive dimension in assessing students' abilities. Moreover, the TAI cooperative learning model is believed to be relevant in enhancing self-proficiency, as well as other mathematical ability dimensions, particularly in Statistics course. Therefore, this study aimed to assess the enhancement of self-proficiency, mathematical problem-solving and mathematical communication by implementing the TAI (Team-Assisted Individualization) Cooperative Learning Model in the context of Non-Parametric Statistics, which is a core undergraduate statistics course. A quasi-experimental approach with purposive sampling, which comprised 72 observation samples divided into control and experimental groups, was used to conduct this study. Evaluation instruments consisted of mathematical problem-solving test, mathematical communication test, and self-proficiency test, along with observation sheets. Furthermore, these statistical analysis tools were used included the Paired Sample t-test, the Independent Sample t-test, as well as the ANCOVA (Analysis of Covariance). The results, obtained through various assessments that examined mean differences and comprehensive statistical analyses, comprised both independent and dependent sample evaluations. The evaluations consistently showed substantial increase in problem-solving ability, communication skills, and self-proficiency in the cohort subjected to the experimental conditions, surpassing those observed in the control group. The ANCOVA estimations further validated the meaningful effect of the teaching strategy on the enhancement of the tested aspects. In conclusion, this study implied that the implementation of TAI learning model effectively enhanced all three objectively and measurably assessed aspects, particularly in the context of non-parametric statistics course.