Chiang and Goldreich investigate the spectral energy distributions (SEDs) of T Tauri stars with passive circumstellar disks. They model the disks as optically thin layers of superheated dust grains that re-emit about half of the stellar energy absorbed, while the other half is emitted inward to regulate the disk's temperature. The heated disk flares, absorbing more stellar radiation, especially at large radii, than a flat disk. The SED from the disk is relatively flat in the thermal infrared, with the surface layer contributing about three times more than the interior at a given frequency. Spectral features from dust grains in the superheated layer appear in emission if the disk is viewed nearly face-on. The authors derive hydrostatic and radiative equilibrium models for these disks and discuss their implications for observations, including the comparison with the SED of the classical T Tauri star GM Aur. They also explore unresolved issues such as the stability of the disk, the dependence of the SED on disk inclination, and the role of molecular lines in covering the thermally emitted spectrum.Chiang and Goldreich investigate the spectral energy distributions (SEDs) of T Tauri stars with passive circumstellar disks. They model the disks as optically thin layers of superheated dust grains that re-emit about half of the stellar energy absorbed, while the other half is emitted inward to regulate the disk's temperature. The heated disk flares, absorbing more stellar radiation, especially at large radii, than a flat disk. The SED from the disk is relatively flat in the thermal infrared, with the surface layer contributing about three times more than the interior at a given frequency. Spectral features from dust grains in the superheated layer appear in emission if the disk is viewed nearly face-on. The authors derive hydrostatic and radiative equilibrium models for these disks and discuss their implications for observations, including the comparison with the SED of the classical T Tauri star GM Aur. They also explore unresolved issues such as the stability of the disk, the dependence of the SED on disk inclination, and the role of molecular lines in covering the thermally emitted spectrum.