Recently established mathematics and science intervention models, designed to increase participation and achievement of Hispanics, women, minorities, and disadvantaged postsecondary students, are reviewed to identify successful organizational designs and key elements. Organizational designs include collaboration between school district, college, or university and industry; college consortium arrangements to work on special projects; institutional block programs to provide academic and student support services to a cluster of math and science students; and student/faculty mentorship. Twenty-six key elements of models designed for Mexican Americans as a main target group are: high level administrative support, departmental commitment and support, collaborative organizational design featuring early student identification and progressive intervention, active staff participation, use of role models, close faculty and counselor contact with students, contact with parents, strong administrative leadership, use of program advisory committees, staff incentives, early recruitment of high ability students, measurable objectives, long-term goals, high student expectations and use of incentives, practical "hands on" learning experiences, development of communication skills, use of ethno-related math and science concepts, use of student learning communities, parental involvement, visits with practicing scientists and mathematicians, remedial/enrichment activities, long-range multiple-source funding, data collection for program evaluation, formative and summative evaluation, quality-verification and replicability, and documented student outcomes. (NEC)