The Portland Mathematics, Engineering, Science Achievement (MESA) program was designed to remedy the underrepresentation of particular ethnic groups in mathematics and science-based careers and professions. It provides enrichment instruction on a weekly basis in eight middle schools and three high schools to enhance mathematics and science skills and direction in career exploration. The 331 students who were in the second year of the program expressed high regard for the program. Virtually all were enrolled in mathematics and science courses; the participants were 42% African-American, 54% female, and 85% in middle schools. Developed collaboratively between the Portland Public Schools and Portland State University, the program is supported by business and industry, including provision for guest speakers, site visits, mentorships, and internships. Expansion of the project resulted in a decline of the percentage of underrepresented groups participating, because of the schools selected. Recommendations for future development of the program are given. Appendices include achievement data, a list of activities, incentives information, and questionnaire results. (MNS)