The need for mathematics educators, schoolteachers and mathematicians to work together to improve K-12 mathematics education continues to be a great concern throughout the world. The main paper for this panel discussion proposes a paradigm or perspective within which to organize this working together of the different groups. This is to see mathematics education as mathematical engineering. From this perspective, the challenge of the mathematics educator and the schoolteacher is to customize mathematics to students’ needs. The role, in turn, of the university mathematician is to customize mathematics courses for teachers so that they in turn may be able to customize the mathematics for the different needs of their students. This paradigm is then discussed in different contexts, in the United States, Hong Kong, Switzerland, and the Philippines. The paradigm is seen to be fruitful in these different contexts.