The aim of this investigation was to determine whether biology majors' and non-biology majors' attitudes toward biology are changed as a result of a single semester of instruction in biology. This study also attempted to determine the direction, degree, and possible correlates of this modification. The Biology Attitude Scale was administered at the beginning and conclusion of two non-biology majors courses and three biology majors courses. Biology majors had significantly more positive entering attitudes toward biology than did the non-biology majors; however, all groups except the biology honors-section had decreased in positive attitudes by the end of the term. Although the decrease was not statistically significant, it was sufficient to result in statistically indistinguishable leaving-attitudes as evaluated by analysis of covariance. This study also demonstrated that the students' attitudes toward biology are only minimally related to such well-defined ideographic characteristics as gender and age. (Author)