This monograph, part of a series about the development of reading processes, focuses on the research about social class and ethnic group differences in learning to read. Among the topics discussed are considerations in the interpretation of research findings, genetic versus environmental explanations of the relationship between socioeconomic status and reading, and intervention-program evaluations and experimental studies concerning socioeconomic status and differences in reading ability. Attention is given to those experimental studies that evaluate expectations of success and language development factors. In addition, dialect-related problems in reading are discussed as they relate to linguistic and social differences associated with dialect usage, to proposed means of teaching the speaker of nonstandard English, and to other methods for exploring dialect differences in reading. A list of references completes the booklet. (KS)