Based on the premise that all commercially available surfactantsare at best simple blends and that many in reality are a complexmixture of surface active species and minor non-surface activecomponents, it rapidly becomes apparent that the prediction ofstructure-performance relationships is far from easy. Thedevelopment of surfactants to meet specific performance criteriarequires a fundamental knowledge of structural features and / orcomponents which contribute to or possess one or more of thedesired surface active properties. Volume 2 of this Annual Surfactants Review series addresses someof these structure / performance considerations, from computermodelling through to a consideration of how to modify specificsurfactants by adjusting carbon chain length distribution, bystudying the influence of chain branching, by introducing reactivegroups or fluorinated hydrophobes, or by replacing conventionalhydrophobes (or hydrophiles) with natural feedstock derivatives.The latter include carbohydrate derivatives, natural hydrocolloidsand biosurfactants. A detailed study of catalytic and kineticeffects in ethoxylation processes shows how nonionic ethoxylatecompositions can be altered, and this is further illustrated by aconsideration of narrow chain length distribution fatty alcoholethoxylates and their properties. Influence of chain branching infatty alcohol ethoxylates is also demonstrated, using secondaryalcohol ethoxylates as an example. Two end-use applications areincluded, not only to report the latest developments in those areasbut also to illustrate the performance / selection approach inidentifying the most appropriate surfactants for a specific enduse.