The purpose of this study was to examine the development of children's understanding of animal death as compared with human death, clarify the order and interrelationships of the concepts of causality, state of death, irreversibility and universality of death, as well as to examine the influence of experience with death and parental explanations on children's understanding of death. Twenty children at each of three age groups (4, 6, and 9 years) were read two animal and two human stories dealing with the topic of death and asked a series of questions designed to assess their understanding of the four concepts. Experience with death and parental explanations were assessed through the use of parental questionnaires. Results indicated children's understanding of the concepts of death increased with age. The most rapid development of the understanding of causality, state of death and irreversibility was indicated between 4- and 6-years-of-age, with universality continuing through 9-years-of-age. Correlations between the UDI subscales for both animal and human death indicated the concepts were unrelated until after six years of age. A developmental progression in the interrelationships of animal with human concepts of death was found. Correlations were significant for causality at 4-years, state of death and universality at 6-years and state of death, irreversibility and universality at 9-years-of age. Experience with human death influenced the human scores for the concepts of causality, state of death and irreversibility. No significant correlations for universality or animals was found. / Master of Science