We report temperature measurements of atoms trapped in a three-dimensi
onal (3D) optical lattice, a well-defined laser-cooling situation that
can be treated with currently available theoretical tools. We also ob
tain fluorescence spectra from a 3D optical lattice, from which we obt
ain quantitative information about the trapping atoms, including the o
scillation frequencies, spatial localization, and a temperature, which
is in good agreement with our direct measurements. For comparison we
study a 1D lattice using the same atom (cesium).