The non-random pattern of genome-wide DNA methylation in mammalian cells is established and maintained by DNA methyltransferases DNMT1, 3A, and 3B. De novo DNA methyltransferase DNMT3B is critical for embryonic development and is mutated in ICF syndrome. Despite its importance in normal cellular functioning, little is known about how DNMT3B operates in the context of chromatin. Here we demonstrate that DNMT3B associates with four chromatin-associated enzymatic activities common to transcriptionally repressed, heterochromatic regions of the genome: DNA methyltransferase, histone deacetylase, ATPase, and histone methylase activities. By immunoprecipitation and GST pull-down, we show that DNMT3B interacts with HDAC1, HDAC2, HP1 proteins, Suv39h1, and the ATP-dependent chromatin remodeling enzyme hSNF2H. Endogenous hSNF2H is also associated with DNA methyltransferase activity. These proteins co-localize extensively with DNMT3B in heterochromatic regions. Our results therefore link DNMT3B to three other components of the epigenetic machinery and provide important insights into how DNA methylation patterns may be established within the chromatin environment. Published by Elsevier Inc.