A series of investigations studied dimensions of individual differences in elementary and secondary school students in ability and "style" in speaking, writing, and other verbal performances; the relations of these dimensions to measured personality characteristics; early childhood and home background factors in these variables; and the relative effectiveness of three teaching methods to improve skills in written composition and performance on verbal ability tests including theme writing. Related studies included one of the dimensions of style in the works of established writers, a study of the tendency to give "opposite" responses in free association tests and its relation to verbal ability and personality, and a study of personality ratings based on experimentally controlled voice samples. Few if any significant relations were obtained between personality measures and measures of speech or writing performance, but several dimensions of ability and style in verbal tests and performances were established. Speaking abilities were shown to be factorially complex, dependent partly on the method of measurement or observation. Significant home background factors in language development were identified. Certain teaching methods ("Fluency,""Structural Grammar," and "Logical Thinking") produced significant improvements in measured verbal abilities. (Author)