Understanding the packaging of DNA into chromatin is essential for the study of gene expression regulatory mechanisms. Heterochromatin establishment and maintenance dynamics have emerged as key features involved in genome stability, cellular growth, and disease. The heterochromatin protein HP1a is the most extensively studied factor that has both establishment and heterochromatin maintenance activities. This protein has two primary domains, namely the chromoshadow and the chromodomain, separated by a hinge region. Several works have taken place over the years, taking the challenge of defining HP1a partners using diverse experimental approaches. We revised and assemble on explaining these interactions and the potential complexes and subcomplexes associated formed with this essential protein. Characterization of these complexes will allow us to clearly understand the consequences of HP1a interactions in heterochromatin in maintenance, heterochromatin dynamics, and the direct relationship of heterochromatin with gene regulation.