This report presents trial school-district-level results of the National Assessment of Educational Progress (NAEP) mathematics 2003, 2005, and 2007 assessments at grades 4 and 8 for 10 urban public-school districts: Atlanta City School District; Austin Independent School District (ISD); Boston School District; Charlotte-Mecklenburg Schools; City of Chicago School District 299; Cleveland Municipal School District; Houston Independent School District; Los Angeles Unified School District; New York City Public Schools; and San Diego City Unified School District. In 2005, Austin ISD was added and also participated in 2007. These districts participated voluntarily in the trial assessment. Data for the District of Columbia, which regularly participates in NAEP, are also included. Student performance is reported in terms of average scale scores on the NAEP mathematics scale and the percentages of students who attained the achievement levels set by the National Assessment Governing Board. Comparisons are made to results for public schools in large central cities. Student performance is reported by race/ethnicity, eligibility for free/reduced-price school lunch, and for students with disabilities and English language learners. At grade 4, between 2003 and 2007, mathematics performance improved in 8 of the 10 districts that participated in both years. Between 2007 and 2005, four districts scored higher and one scored lower. At grade 8, eight districts had higher scores in 2007 than in 2003, and six had higher scores when 2007 was compared with 2005. (Contains 9 tables and 2 figures.)