The packaging of genomic DNA into chromatin, often viewed as an impediment to the transcription process, plays a fundamental role in the regulation of gene expression. Chromatin remodeling proteins have been shown to alter local chromatin structure and facilitate recruitment of essential factors required for transcription. Brahma-related gene-1 (BRG1), the central catalytic subunit of numerous chromatin-modifying enzymatic complexes, uses the energy derived from ATP-hydrolysis to disrupt the chromatin architecture of target promoters. In this review, we examine BRG1 as a major coregulator of transcription. BRG1 has been implicated in the activation and repression of gene expression through the modulation of chromatin in various tissues and physiological conditions. Outstanding examples are studies demonstrating that BRG1 is a necessary component for nuclear receptor-mediated transcriptional activation. The remodeling protein is also associated with transcriptional corepressor complexes which recruit remodeling activity to target promoters for gene silencing. Taken together, BRG1 appears to be a critical modulator of transcriptional regulation in cellular processes including transcriptional regulation, replication, DNA repair and recombination.