This article reviews how various thickeners work and their value to the industry. The different types of thickeners that are available for waterborne adhesives will be identified, and the selection process is discussed to assist the formulator in choosing the correct thickener for his or her formulation. The flow behavior of a waterborne adhesive is an important processing parameter in many applications. Adhesives that must be applied as coatings or adhesives that must not flow or sag before cure are applications that use thickeners in the formulation.Thickeners are additives that are often used to adjust the rheology of most waterborne adhesives. Aside from viscosity modification, thickeners provide multiple functions including suspension of formulation ingredients, improved coating characteristics, improved stability, moisture retention, etc. Thickeners and plasticizers together account for the largest dollar value of additives that go into adhesives. They represent 55% of the total additive market.