Workers in both animal communication and behavioral ecology have long been interested in animal signals. Animal-communication researchers often have a background in ethology or comparative psychology, and place priority on signal analysis, whereas modern behavioral ecologists are concerned with the effects of natural selection on the exaggeration or development of a trait. Although the two fields examine the same problems, this division has hindered the solution of the problems themselves. Recent theoretical and empirical work has started to bridge the gap, but several important questions, particularly regarding sexual selection, have remained unanswered. Here I examine the differences in these two approaches to the study of animal signals, and suggest additional areas that would benefit by combining the two viewpoints.