We studied the selection of calling sites by the emerald-eyed treefrog (Hypsiboas crepitans) based on microhabitat factors and body size using a resource selection probability function, determined by a multiple logistic regression model. Distance from the pond edge was the most reliable predictor of frog calling site. A significant difference in body size was found between frogs calling: in the pond, at the edge, far from the pond, on plants, and on rocks. Frogs at the edge of the pond were larger than frogs calling far from the edge.