The IMP curriculum integrates the four years of mathematics that are traditionally presented as separate courses in algebra, geometry, trigonometry, and precalculus. In addition, IMP exposes students to important concepts that are derived from probability and statistics. IMP targets all students, including those who are at risk of leaving school before they have graduated, and groups of students who have traditionally been underrepresented in mathematics courses.

Webb and colleagues conducted focus studies on student achievement in statistics and other topics emphasized in the curriculum. In all three studies, after controlling for differences in mathematics achievement prior to entering high school, the IMP students significantly outperformed their counterparts from the traditional algebra, geometry, trigonometry, and precalculus curriculum.

A study of transcripts of more than 1,000 students in three high schools revealed that a higher percentage of IMP students took at least three years of college-preparatory mathematics than students enrolled in the traditional algebra-geometry-calculus sequence. This finding was true for both female and male students and for all ethnic groups of significant size, at each of the three schools in the study.

Webb and colleagues are providing the National Science Foundation with information about:

- the long-term effects of IMP on students who have completed at least three years of the curriculum;
- the in-service needs of teachers who implement the program;
- the rate at which underrepresented students successfully complete three and four years of the curriculum;
- the levels of curriculum implementation that are necessary to produce quality instruction; and
- the variations in implementation that are necessary to adapt the curriculum to specific situations.

Because the program is problem-based rather than subject-based, IMP students learn how to define problems and conduct mathematical analysis using a variety of skills and approaches, drawing on more than one of the traditional subject areas at once. IMP began as a response to a request for proposals from the California Postsecondary Education Commission in 1989. The program is in use in more than 100 sites in 11 states.