The nest and nesting behaviorof a pair of Red-crowned Ant-Tanagers ( Habia rubica rubica) from Paraguay is described. Results are compared with those from studies of other subspecies. Because the species occurs in temperate, subtropical, and tropical habitats from Mexico south to Paraguay, northern Argentina, and southeastern Brazil, we expected details of breeding to differ in different parts of the range. Other than differences in the timing of breeding north and south of the equator, only details of nest structure and egg coloration showed geographic variation.