Ion cyclotron waves are used to heat hydrogen plasma in the Proto-Cleo ℓ = 3, seven-field-period stellarator. RF power is coupled to the net current-free plasma by a singleturn magnetic dipole antenna oriented to produce RF magnetic flux from the high-field side of the plasma. Both ion and electron heating are observed – from 50 to 150 eV and 6 to 15 eV, respectively. RF probes show radial and toroidal penetration of the RF magnetic fields. Particle confinement is not reduced by the RF for densities higher than 1012 cm−3. Thermal loss rates increase, however, with RF heating, though the reduction in energy confinement seems to be a result of particle heating and not of RF-enhanced diffusion.