This study aims to develop a test instrument based on ethnomathematics in the context of rail and retail to assess students’ mathematical literacy. Rail and retail are two essential elements in the development of modern urban areas, where rail-based transportation systems such as MRT and KRL; while retail is developing of shopping centers, such as malls, which play a significant role in supporting urban mobility. The research method used is Research and Development (R&D), following the Borg & Gall model, which consists of 10 stages. The instrument was developed based on three of the mathematical literacy indicators outlined in PISA (formulate, employ, and interpret) for 27 questions. The research involves six mathematics teachers and three mathematics education lecturers as validators of the instrument, and students from SMAN 8 South Tangerang City, a total of 120 students as subjects for the test trial. Based on the results, using Aiken’s coefficient the instrument ware declared valid and testing using Cronbach’s Alpha get 0,964 (very high level of reliability). In addition, item difficulty and discrimination indices were analyzed to assess the quality of the instrument quantitatively. Thus, it can be concluded that the rail and retail ethnomathematics-based test instrument is declared valid and can be used to measure mathematical literacy abilities. Penelitian ini bertujuan untuk mengembangkan instrumen tes berbasis etnomatematika rail dan retail untuk mengukur kemampuan literasi matematis. Rail dan retail merupakan dua elemen penting dalam pengembangan wilayah perkotaan modern, di mana sistem transportasi berbasis rail seperti MRT dan KRL, sedangkan retail berhubungan dengan petumbuhan pusat perbelanjaan seperti mall berperan besar dalam menunjang mobilitas masyarakat urban. Metode penelitian yang digunakan adalah Research and Development (R&D) dengan model Borg & Gall yang terdiri atas 10 tahapan. Instrumen disusun berdasarkan tiga indikator kemapuan literasi matematis dalam PISA (formulate, employ, interpret) sebanyak 27 item soal. Penelitian ini melibatkan enam guru matematika dan tiga dosen pendidikan matematika sebagai validator instrumen, dan siswa SMAN 8 Kota Tangerang Selatan sebagai subjek ujicoba instrumen sebanyak 120. Berdasarkan hasil penelitian, menunjukkan bahwa dengan menggunakan Aiken’s instrumen dinyatakan valid, dan berdasarkan uji reliabilitas menggunakan Cronbach’s Alpha diperoleh 0,964 (kategori reliabilitas sangat tinggi). Dengan demikian dapat disimpulkan bahwa instrumen tes berbasis etnomatematika rail dan retail dinyatakan valid dapat digunakan dapat untuk mengukur kemampuan literasi matematis.