H Retnawati1, Kismiantini1 and O A Montesinos-López2 1 Mathematics Education Department, Universitas Negeri Yogyakarta, Indonesia 2 Faculty of Telematic, Universidad de Colima, MexicoWe are honored to present a collection of articles from the 3nd International Seminar on Innovation in Mathematics and Mathematics Education (ISIMMED 2019) which was conducted in Universitas Negeri Yogyakarta, Indonesia from 3 to 4 October 2019. In accordance with the development of science and technology, the practice of research activities and learning activities needs to be adjusted. This adjustment needs to be linked to Science, Technology, Engineering and Mathematics (STEM). All of us know that the course on STEM is inseparable from mathematical content such as algebra, geometry, analysis, applied mathematics, statistics, and computing, and also teaching and learning.With the theme of “Innovation in STEM Education: Current Research Trends and Practices”, this seminar discussed the growth of technology that gave many impacts in all part of life, particularly in mathematics and mathematics education. The sub theme is research in STEM Education, teaching and instruction in stem education, assessment in stem education, ethnomathematics, statistics and its applications, algebra and its applications, geometry and its applications, analysis and its applications, and computer science and its applications. We hope that this proceeding will generate innovative concepts and practices in mathematics and mathematics education, and as an attempt to build competitive human resource for researchers, educators, practitioners and policy makers to share their experiences during the ISIMMED 2019. After a series of review process, 72 articles are selected to be published in this Scopus-indexed proceeding. The remaining articles are published in the regular proceeding.The editors and the committees of ISIMMED 2019 would to thank the participants who have contributed and shared their scientific works in this proceeding. We also would to express our gratitude to every committee member for organizing the conference and to Universitas Negeri Yogyakarta for the financial support.2 March 2020EditorsHeri RETNAWATIKISMIANTINIOsval Antonio MONTESINOS-LÓPEZList of Committees are available in the pdf.