The Special Education Elementary Longitudinal Study (SEELS) is a national study of the characteristics, experiences and achievements of students with disabilities in elementary and middle school. This report presents results of data (mainly surveys of and interviews with parents) on more than 12,000 students with disabilities, ages 6-12, selected to represent all 12 federal special education categories. The study will collect information on students three times over 4 years. This report focuses on demographic characteristics of students and their households. After an introductory chapter, chapter 2 (titled "Demographic Characteristics of Elementary and Middle School Students Receiving Special Education" by Camille Marder and Mary Wagner) describes the disability classifications and demographic characteristics of students with disabilities, comparing them to nondisabled students and highlighting differences among disabilities. Chapter 3, titled "Characteristics of Students' Households" by Mary Wagner and others, provides detailed data on household composition (living arrangements, household size, disability prevalence, and disability differences), parents' characteristics (age, education, employment, disability differences, and demographic differences), and economic status (income, experience with benefit programs, children's health insurance coverage, transportation and telephone. A summary chapter highlights key findings and an appendix addresses methodological issues related to study design, sample, and analysis. (Contains 28 references and 32 exhibits.) (DB)