We are interested in eukaryotic chromosomes and the processes that affect them including transcription, DNA replication and repair, and segregation. Our published work has focused on a single chromosomal domain within the genome of the model yeast Saccharomyces cerevisiae. This domain is assembled into a repressive chromatin structure that serves as a paradigm for the structure, function and heritable nature of heterochromatin that plays key roles in human development and disease. We study the proteins that regulate the assembly of this chromatin structure at a mechanistic level combining genetic, molecular and biochemical approaches.