We calculate the thermodynamic functions of a hot gluon plasma to leading o
rder in hard-thermal-loop (HTL) perturbation theory. Effects associated wit
h screening, gluon quasiparticles, and Landau damping are resummed to all o
rders. The ultraviolet divergences generated by the HTL propagator correcti
ons can be canceled by a counterterm that depends on the thermal gluon mass
parameter. The HTL thermodynamic functions are compared to those from latt
ice gauge theory calculations and from quasiparticle models. For reasonable
values of the HTL parameters, the deviations from lattice results for T>2T
(c) have the correct sign and roughly the correct magnitude to be accounted
for by next-to-leading order corrections in HTL perturbation theory.