This study explores the challenges of implementing computerized adaptive testing (CAT) for mathematics assessment among prospective elementary school teachers in Indonesia. It aims to describe (1) assessment practices of mathematics lecturers and (2) challenges in adopting CAT. Using a qualitative phenomenological approach, data were collected from 17 mathematics lecturers across Indonesia through questionnaires followed by in-depth interviews with four lecturers unfamiliar with or struggling to use CAT. Findings indicate that paper-and-pencil tests and computer- based testing (CBT) dominate university assessments. Key barriers to CAT adoption include limited lecturer knowledge and skills, technical constraints, inadequate infrastructure, and incompatibility with essay-based assessments. Despite these challenges, lecturers express interest in a more accessible and cost-effective CAT. The study concludes that lecturers acknowledge CAT's potential to enhance fairness and accuracy in testing while they face difficulties in its implementation. A targeted CAT development program aligned with lecturers' needs with institutional support is essential for successful integration. CAT has the potential to improve assessment effectiveness and efficiency in Indonesian universities aligning with technological advancements and 21st century education trends.