Publisher Summary This chapter discusses the adhesion of cell. The coating of a solid adherend by a liquid adhesive, in terms of wettability, surface irregularity, and penetrability is described in the chapter. Adhesive phenomena are considered to play an important part in morphogenesis and in the metastasis of malignant disease. These aspects of adhesion are also reviewed in the chapter together with relevant information obtained from studies of cell cultures. The adhesion of two surfaces may result from their mechanical interlocking and/or interfacial forces. Chemical bonds are not usually considered as “adhesive” bonds in the physical sciences. Van der Waals' forces are also involved in adhesion. These may be further classified as (1) London forces, (2) Debye forces, and (3) Keesom forces. An estimate of the work of adhesion between two solids may be obtained from the “adhesion number.” In this method, quartz particles were allowed to settle onto a quartz plate. The particles were then counted. After this, the plate was inverted and the remaining particles were counted. This number expressed as a percentage of the total number of particles originally present on the plate was termed the adhesion number and gave a measure of the adhesion between the particles and the quartz surface. Modifications of this method, by which cells adhering to surfaces are detached by a stream of fluid instead of gravitational forces, are described by Fenn.