In order to assess the effectiveness of the Continuous Progress in Spelling program, an individualized approach to spelling mastery, this study investigated the relationships among grade level, reading ability, spelling achievement, and attitude changes, in third- and fourth-grade participants of the program. A total of 689 students from five elementary schools in Kent County, Maryland, were tested on spelling achievement, reading ability, and attitudes toward spelling. The experimental group, consisting of 323 students, then received individualized spelling instruction according to program specifications. Posttesting revealed significant differences in achievement between grade levels and treatment groups. Across all levels, students in the experimental group showed greater spelling ability than did those in the traditional spelling program. The fact that both teachers and students showed more positive attitudes toward spelling in the experimental situation suggests a possible relationship between those attitudes and spelling achievement. (Author/KS)