A persistent problem in education is underrepresentation of certain cultural and linguistic groups such as American Indian, African American, and Hispanic, in special programs for exceptionally talented students, especially in science, technology, engineering, and mathematics (STEM). An assessment with demonstrated reliability and validity as an instrument to identify exceptionally talented students was included with new instruments created in the X project. A continuum of problems, including closed, semi-open, and open-ended, was an important component of the assessment, enabling the assessment of creativity as well as understanding of mathematics concepts. The math assessment was field tested in five high schools in high poverty areas that also had high percentages of American Indian or Hispanic students. It was implemented as part of a battery of instruments to identify students to participate in a special internship program. The test-retest reliability and construct, concurrent, and predictive validity need to be investigated in future studies.