Teachers should have the necessary assessment knowledge and skills to contribute to students' learning. This study provides insight into how a professional development program for teachers contributed to the achievement of higher mastery levels of assessment literacy. This study used Xu and Brown's TALiP (Teacher Assessment Literacy in Practice) framework to achieve these higher levels. To evaluate the extent to which teachers demonstrated professional growth regarding their assessment literacy, teachers' practices were evaluated through a content analysis of summative assessments. Potential changes in teachers' knowledge, skills, and beliefs were measured through questionnaires and interviews. The outcomes showed that reflection on educational goals and on teachers' beliefs, collaborative practice, and peer feedback played an important role in fostering higher mastery levels in assessment literacy. The outcomes of this study support the value of the TALiP framework and support the idea that professional growth could be fostered via diverse growth pathways.