The National Assessment of Educational Progress (NAEP), in partnership with the National Assessment Governing Board and the Council of the Great City Schools (CGCS), created the Trial Urban District Assessment (TUDA) in 2002 to support the improvement of student achievement in the nation's large urban districts. The TUDA focuses attention on urban education and measures educational progress within participating large urban districts. TUDA results are based on the same mathematics and reading assessments used to report national and state results, thus allowing students' performance in the 21 participating districts to be compared to the performance of their peers in the nation's large cities as well as their home state. The NAEP mathematics assessment measures students' knowledge and skills in mathematics and students' ability to apply their knowledge in problem-solving situations. The NAEP reading assessment measures students' reading comprehension by asking them to read selected grade-appropriate materials and answer questions based on what they have read. Student performance is reported as average scores on separate 0 to 500 scales in mathematics and reading, and as percentages of students performing at or above three achievement levels (Basic, Proficient, and Advanced). Changes in students' performance over time are noted only if the differences in scores or percentages are determined to be statistically significant (p less than 0.05). This report provides the results of the 2013 assessments in mathematics and reading at grades 4 and 8 in the following areas: (1) performance of large cities; (2) performance of urban districts; (3) progress of urban districts; and (4) progress of various student groups in urban districts. (Contains 2 tables and 5 figures.) [This report was prepared for the National Center for Education Statistics under Contract No. ED-IES-13 C-0017 with Educational Testing Service. For the executive summary, see ED544546.]