This study provides evidence of the significant life experiences , which influence advocates for nonhuman animals to develop sensitivity toward animals. Thirty-nine humane educators participated in an online survey. Findings indicate that having a relationship with a companion animal in adulthood is the most important life experience, followed by having a childhood experience with an animal, being exposed to a positive role model in childhood, and reading about animals and animal issues. The study did not find age and gender related (...) differences in life experiences. This paper compares the results from this study to two previous studies. The first study examined the SLEs of animal advocate leaders through analysis of autobiographies, biographies, oral histories, and written interviews. The second study examined the SLEs of animal rescuers through an open-ended survey. This paper discusses similarities and differences among these three groups. (shrink)