Formation of inorganic deposits or scale is a serious issue for industries that process large quantities of water. These deposits increase energy consumption by heat transfer units, hinder separation and transport processes, and mandate regular shutdowns for cleaning. One approach for mitigating this problem is the use of chemical additives that slow crystal growth processes leading to deposit formation. These additives work primarily by adsorbing to developing nuclei and growing crystal faces to slow the further incorporation of mass. These interactions are poorly understood and information to guide the selection of an effective treatment chemical is not readily available. In this presentation, research aimed at identifying the optimal structure for polymeric additives used to inhibit scale formation will be reviewed. Discussed will be the use of polymeric additives to inhibit calcium carbonate scale formation in kraft pulping liquors, which are processed at high temperatures and supersaturations. The focus will be on carboxylic acid containing polymers, whose performance appears to be strongly dependent on its structural characteristics. Naturally occurring polymers such as lignin along with synthetic co- and terpolymers produced from maleic and acrylic acid monomers will be of particular interest. The most effective molecular weight distributions will be identified and possible explanations for this dependency will be discussed. Also reviewed will be the role of other structural characteristics such as the concentration of carboxylic acid functional groups and their distribution throughout the polymer backbone and the role of chain flexibility.