This research mainly focuses on: (1) the development of Realistic Mathematics Education (RME), (2) improving the effectiveness of Mathematics learning with the application of RME, and (3) constraints and solutions in the implementation of RME for primary schools prospective teachers.This research was conducted in the Primary Teacher Education Program of Teacher Training and Education Faculty of Sebelas Maret University, using the Research and Development (R & D) and implementing Classroom Action Research (CAR). The research subject included 71 students attending Basic Mathematics II in Academic Years 2015/2016. Data were validated using data and methodological triangulations. Afterwards, they were analyzed using qualitative analysis comprising three streams of activities: data reduction, data display, and conclusion drawing. Research procedure used was CAR with series of cycles involving such steps as (1) planning, (2) action, (3) observing, and (4) reflecting which was conducted simultaneously.The research finds out that: (1) Five steps of the implementation of RME for prospective teachers of primary school are (a) understanding daily problem/ context, (b) explaining contextual problem, (c) solving contextual problems, (d) comparing and discussing answers, and (e) drawing conclusion. (2) The implementation of RME can improve the effectiveness of Mathematics learning, (3) constraints in the implementation of RME include: (a) students do not have adequate understanding on Mathematics teaching materials, (b) students are not familiar enough with problems in learning Mathematics related to problems in daily life, (c) students are not quite familiar with the usage of teaching media in Mathematics learning, (d) students do not well master various approaches in Mathematics learning, (e) students do not acquire skill well in arranging lesson plans for Mathematics learning, and (f) students are not skilled enough in the simulation of Mathematics learning. Meanwhile, solutions for the difficulties are reinforcement and assistance in: (1) the mastery of teaching materials, (2) the relationship between teaching materials and problems in daily life, (3) uses of media/visual aids for Mathematics learning, (4) the mastery of various approaches and methods in Mathematics learning, (5) the arrangement of lesson plans in Mathematics learning, and (6) simulation of Mathematics learning.