This research perspective focuses on three of the disciplinary areas that have engaged my interest as a professional biologist. My research first focused on life history evolution, but it expanded to include the evolution of viviparity, and developmental biology. My subjects are squamate reptiles, although I do hands-on research largely with lizards. A common theme of the research that I discuss here is the role of eggs and embryos in ecological and evolutionary studies and why that role may be critical to the resolution of important biological problems. In this perspective, I summarize highlights of my major research projects since 1971: 1) life history evolution of West Indian island and mainland Anolis lizards; 2) long-term studies on the demography and egg survival of a small, r-selected Panamanian anole; 3) ecological and physiological studies on the transition between oviparity and viviparity in Sceloporus; 4) costs and benefits of the novel rigid-shelled egg of gekkotan lizards; and 5) embryonic adaptations to low oxygen availability in rigid-shelled eggs of gekkotan lizards. I put these projects in the context of my own developmental trajectory as a biologist; my research has shifted from population biology to embryonic development without breaking the connection between these seemingly disparate disciplines.