Adherent cell lines grow attached to the surface of a cell culture vessel. Due to the adherent nature of the cells, enzymes, such as trypsin, are required to lift the cells from the cell culture vessel for harvesting or subculturing. Many cancer cell lines are adherent, rendering adherent cell culture a critical experimental method in the fields of cell biology, biochemistry, and cancer research. In this chapter, we outline the protocols for culturing and maintaining adherent cells. We detail the procedures for preparing cell culture medium, thawing and reviving frozen adherent cells, subculturing adherent cells, freezing cells, and counting cells. Most notably, we outline the best techniques and practices for optimal growth of healthy adherent cells while diminishing the risk of contamination.