This paper provides an overview of a programmatic research project, the Enactment Project, at the National Institute of Education in Singapore. The project studies the enactment of school mathematics by competent experienced teachers in secondary schools and also how widespread practices of these competent experienced teachers are in the classrooms of mathematics teachers in general. It elaborates the two studies and two phases of the project. [This paper is the first in a symposium of four papers. For the second paper "Instructional Strategies Adopted by Experienced Secondary Teachers When Enacting the Singapore School Mathematics Curriculum," see ED604247. For the third paper "Chronologically-Grounded Survey," see ED604248. For the fourth paper "Singapore Secondary Mathematics Pedagogy: The DSR DNA," see ED604249.]