In this article I tell how my encounters with the animal-rights movement gradually reshaped my thinking about the ethics and practice of animal experimentation. Early experiences, including a panel discussion memorably described as “Christians and Lions,” where Professor Gary Francione sharply challenged my defense of LD₅₀ testing, forced me to reconsider assumptions I had long taken for granted. Rather than producing an immediate change, these encounters led me to learn more by engaging directly with critics and their organizations. Over time my views evolved toward strong support for the “Three R’s” replacement, reduction, and refinement of animal use. I also tried to apply these principles by developing computer tools to improve experimental design and alternatives to animal testing. I hope the story illustrates how thoughtful criticism, even when uncomfortable, can stimulate reflection and gradual change.