We predict the density of Triton, as a function of radius, based on the assumptions that it was captured from solar orbit and thus has a rock/ice ratio similar to that of the Pluto--Charon system. The best present estimates for Triton's radius are 1000--2000 km, and if our origin hypothesis is correct, its density should be greater than 2.0 g cm-3, increasing slowly with radius. On the other hand, if Triton is an original regular satellite whose orbit has been perturbed, its density will be lower and more consistent with the derived rock fractions of other icy satellities. ¿ American Geophysical Union 1989