Submillimeter continuum observations of 29 pre-main-sequence objects in Taurus and Orion are used to study the wavelength dependence of particle emission. These objects are mostly T Tauri stars whose long-wavelength emission is thought to originate in circumstellar disks. The flux densities imply power-law frequency distributions with spectral indices between 2 and 3 in almost all cases. If the emission is optically thin, the particle emissivities have power-law indices between −1 and 1; otherwise, these values are lower limits. It is argued that in most cases the emission is optically thin at wavelengths near 1 mm, so the measured incides should be close to the true values