The GHz Peaked Spectrum (GPS) and Compact Steep Spectrum (CSS) sources are compact, powerful extragalactic radio sources with well defined peaks in their radio spectra (near 1 GHz in the GPS, and near 100 MHz in the CSS). The GPS sources are entirely contained within the extent of the narrow-line region (< 1 kpc) while the CSS sources are contained entirely within the host galaxy (< 15 kpc). The GPS and CSS sources are likely to be young and evolving radio sources which will become large scale sources. Combining the bright GPS and CSS samples with the 3CR results in a sample spanning a range in source size of 100,000 which can be used to study source evolution. Thus, the GPS and CSS sources are important probes of their host galaxies and will provide critical clues to the origin and evolution of powerful radio sources.