The relationship of socioeconomic status to the reading achievement of Anglo, Mexican-American, and black pupils was investigated in a sample of 144 third- and fifth-grade pupils. Pupils who participated in a free lunch program were classified as belonging to the poverty group; those who did not participate were classified as nonpoverty. At both grade levels, the Anglo group and the nonpoverty group scored significantly higher in measured reading achievement than did the other groups. There was a significant interaction between group membership and socioeconomic status at both grade levels. In the poverty classification there were no significant differences among the three groups, but in the nonpoverty classification the Anglo group achieved a higher level than either the black or the Mexican-American group. (Author/AA)