The transcriptional regulatory system plays a central role in directing gene expression changes in response to internal and external stimuli. In this talk, I will present our group's computational studies on transcription regulation in yeast, ranging from large-scale experimental studies to computational analyses of regulatory networks. In the first half I will introduce results from ChIp-chip experiments that identify genome-wide DNA-binding sites of transcription factors, particularly focusing on the cell cycle regulatory system. In the second half I will discuss how these observations fit in with the idea of a genomic regulatory network, and examine the effects of such networks on gene expression levels. Finally, I will introduce the concept of dynamic network usage in the context of transcription regulation, and how specific regulatory pathways are employed to bring about these transitions.