Thin nanocrystalline silicon (nc-Si) films deposited by plasma enhanced chemical vapor deposition (PECVD) exhibited room-temperature photoluminescence in the visible range of the electromagnetic spectrum. High resolution transmission electron microscopy revealed that the films are made of Si crystals with dimensions 2-15 nm. The photoluminescence spectra of the nc-Si films were similar to the spectra observed from porous silicon produced by anodization and electrochemical dissolution of crystalline Si. This similarity suggests that the luminescence mechanism of nc-Si films is similar to the mechanism of light emission from porous silicon. The ability to manufacture luminescent Si films by methods which are compatible with the current Si based technology, such as PECVD, can provide new possibilities in the realization of optoelectronic devices.