In this article we discuss known and possible uses of echolocation by humans. We argue that echolocation may be a basic perception-action ability of humans. We review studies which suggest that both blind and sighted humans are capable of substantial precision in the perception of properties of distal objects, such as distance, size, shape, substance, and relative motion. We analyze relations between acoustic pulse and echo that may provide information to support these percepts and others. Our analysis predicts echolocation-based sensitivity in humans and other animals to a number of properties of the animal-environment interaction. We also discuss echolocation-based acoustic specification of time-to-contact. We develop a new variable that provides this information and discuss “acoustic s” recently developed by Shaw, McGowan, and Turvey (1991) and by Lee, van der Weel, Hitchcock, Matejowsky, and Pettigrew (1992). Our analysis suggests that there may be important insights to be gained from an ecological study of echolocation in humans and other species. We end with suggestions for research derived from our analysis. © 1995, Taylor & Francis Group, LLC. All rights reserved.