We assessed the impact of a year-long, school-based humane education program on younger (first and second graders) and older (fourth and fifth graders) children's attitudes toward the treatment of animals. Generalization to human-directed empathy was also measured. Using a pretest-posttest design and ANCOVA, we found that the program enhanced the animal-related attitudes of children differentially, depending on grade level. For younger children, there was no significant difference between experimental (E) and control (C) group attitude means; however, qualitative analysis showed that greater enhancement of attitudes occurred for first grade E group children than for C group children at that grade level. No differences were present on the generalization measure of empathy. For older children, there was a significant difference between E and C group attitude means qualified by grade level—there was greater enhancement of humane attitudes for E group than for C group fourth graders but no difference for fifth graders. On the generalization measure of empathy, posttest means for the E group were significantly greater than means for the C group regardless of grade level. The results contribute to the growing literature on the relation between children and animals and serve to encourage and validate the efforts of humane educators to improve children's caring and kindness toward companion and noncompanion animals.