This report presents the results of a battery of sentence combining tasks included in the assessment of writing conducted by the National Assessment of Educational Progress in 1978-79. The first section of the report provides background information about the NAEP survey and discusses the procedures used to develop and score the sentence combining tasks. The second section presents the 14 sentence combining tasks that were administered to 9-, 13-, and 17-year-old students across the United States, along with the most acceptable combination, and the percentage of students who produced acceptable responses. The third section offers a break down of the results according to geographical region, sex, race, education level of parents, and type of community. It also relates student performance on the sentence combining tasks to their primary trait or holistic essay scores and to syntactic descriptions of the sentences comprising their essays. The fourth section provides a summary of the results. Appendixes contain frequency rankings of correct papers and descriptions of the writing exercises and scoring procedures. Primary type of information provided by report: Results (Secondary Analyses) (Interpretation). (FL)