Comparative psychology has undergone many changes since its inception in Victorian England some 100 years ago. Gone are the amusing anecdotes of pet owners and amateur naturalists, replaced by the detailed observations of behavioral scientists made under carefully controlled conditions. Yet, many of the persistent problems in the comparative analysis of intelligence remain: Are the cognitive processes of animals like those of humans? Can researchers construct a phytogeny of intelligence? What is cognition without language? This article briefly reviews the history of the study of comparative cognition. It then discusses 2 of the most active and important areas of empirical inquiry-memory and conceptualization-to acquaint readers with contemporary research in the field. Given increased contact with the related areas of cognitive science, behavioral neuroscience, and behavioral ecology, comparative cognition should continue in its 2nd century to make significant contributions to the overall understanding of the principles of behavior. How familiar a scene it is. A learned and eloquent scientist gazes upward toward the distant heavens, sighs wistfully, and plaintively asks "Is there life beyond earth? Is that life intelli-gent? If so, can we communicate with it?" What a noble quest: to search out alien life and to interact with it. A quest not only noble but also generously funded by governmental agencies. Radio telescopes, orbiting satellites, and both staffed and unstaffed cosmic expeditions have been and will be constructed and undertaken to find extraterrestrial life-at great public expense and with much media fanfare. I wish not to demean these important efforts but rather to suggest that an equally challenging and probably more fruitful search for alien intelligence can take place-right here on earth. Thousands of species of animals inhabit this planet, many of them exhibiting notable craft, flexibility, and ingenuity in adapting to the numerous challenges of survival. The careful and scientific study of our planetmates may shed considerable light on the nature of intelligence, on the character of cognition without language, and on the very possibility of communication with extraterrestrial life-if it is ever found. Perhaps most important, comparing the intelligence of many species of animals may help us know better what it means to be human. Although the study of animal intelligence has been an ongoing concern of scientists for some 100 years-Romanes's (1883/ 1977) classic book, Animal Intelligence, was published in 1883-most people know very little about it. The present popularity of many nature programs on television plus the great publicity that several research projects on animal behavior have recently received suggest that now might be an opportune time to out