Winds are directly detected from solar-type stars only when they are very young. At ages ~ 106 yr, these stars have mass loss rates ~ 106 times the mass flux of the present solar wind. Although these young T Tauri stars exhibit ultraviolet transition-region and X-ray coronal emission, the large particle densities of the massive winds lead to efficient radiative cooling, and wind temperatures are only ~ 104 K. In these circumstances thermal acceleration is unlikely to play an important role in driving the mass loss. Turbulent energy fluxes may be responsible for the observed mass loss, particularly if substantial magnetic fields are present.