Determining the effect of pupils' levels of conceptualization of words on reading achievement was the purpose of this study. Levels of conceptualization was measured ona multiple-choice test using three categories of word definitions: abstract, functional and verbalism. The abstract category was interpreted to be abstract conceptualization and consisted of word definitions that involved either synonyms, antonyms or classifications. The functional category was interpreted to be concrete conceptualization and included responses that indicated action or use of a word. Verbalism category included responses that were non-distinguishing or repeated the stimulus word and was considered to be at the concrete conceptualization level.Using stimulus words taken from basal readers, the multiple-choice vocabulary test, named the Levels of Meaning Test, was designed to measure the three levels of conceptualization. Each multiple-choice item included an abstract, functional, and verbalism definition. Students were asked to choose one of the three definitions provided for a stimulus word that they preferred, Satisfactory reliability and validity for the Levels of Meaning Test were found with pilot studies. Vocabulary difficulty in the Levels of Meaning Test was controlled to be no more difficult than fifth grade level, and the test was read aloud to the students to minimize differences in reading ability.Two-hundred-ninety-eight fifth graders from a middle size Mid-western city were tested with the Levels of Meaning Test,. Results on the Levels of Meaning Test were correlated with reading achievement, intelligence, sex, ethnicity, and socioeconomic status. Reading achievement was determined by comprehension and vocabulary subtests of the Gates-MacGinitie Reading Test, Level D. Intelligence was measured with-cthe California Test of Mental Maturity, Short Form, which yielded a verbal, non-verbal, and total I.Q.. Socioeconomic status was rated middle or lower classification according to occupation of head of household. Ethnicity was classed as either white or non-white on the basis of appearance; the non-white population being exclusively Negro. Results of the reading achievement and intelligence test indicated that the sample population approximated national norms in reading ability and intelligence.Correlating responses according to the three levels of meaning with reading achievement resulted in significant correlations, Students who scored high on abstract responses did significantly better on the subtests of the reading achievement test than students who scored high on functional and verbalism responses. Similarly, responses on the Levels of Meaning Test, were positively, significantly correlated with verbal I.Q. Non-verbal and total I.Q. also correlated significantly with levels of meaning though not to the high degree of verbal I.Q..Socioeconomic status was significantly correlated. Middle classification status was positively correlated with responses on the abstract category. Ethnicity was also significantly correlated with the Levels of Meaning Test; white students chose abstract responses more frequently than the non-white students. No significant correlation was found between sex and levels of conceptualization on the Levels of, Meaning Test.Using the multiple regression technique, variables in combination that predicted abstractual levels of conceptualization were high reading achievement, high verbal I.Q., and white ethnicity. Low reading achievement, low verbal I.Q., and non-white ethnicity predicted high scores in the functional and verbalism categories.Results of this study indicated that the ways fifth graders in this sample population conceptualized words were important to reading achievement. Predictive models of students apt to be abstract or concrete conceptualizers were found. Implications for instruction were that concrete conceptualizers should be given special consideration in developing word meaning to facilitate comprehension and subsequent achievement.