A longitudinal study of the effects of an early childhood mathematics intervention was conducted in 2 private elementary schools in a large city in central Texas. The study included 377 participants in prekindergarten through fifth grades. Explicit non-inverted number names were taught in English and Spanish to prekindergarten and kindergarten students, with formative assessments conducted during this timeframe. Summative assessment results from standardized achievement tests were collected in grades 1 through 5 from 341 of the participants. Normal curve equivalent scores of total mathematics achievement, problem solving, and mathematics procedures were compared among groups of children with no or up to 2 academic years of experience using explicit non-inverted number names. Children in Grade 1 who had no experience with the intervention, scored significantly higher than the other children in mathematics procedures. After the first grade, a means trend emerged, showing children with the most experience demonstrated higher overall mean scores within the three measures. In Grade 3, children with the most experience using the intervention demonstrated significantly higher scores in mathematics procedures. [The dissertation citations contained here are published with the permission of ProQuest LLC. Further reproduction is prohibited without permission. Copies of dissertations may be obtained by Telephone (800) 1-800-521-0600. Web page: http://www.proquest.com.bibliotheek.ehb.be/en-US/products/dissertations/individuals.shtml.]