Biological processes rely upon the specificity of biomolecular interactions. Shape-selective transport and catalysis are facilitated by proteins that show high selectivity for specific carbohydrates, nucleotides, lipids. or peptides. Contemporary chemists are striving to create synthetic receptors that will show similar levels of selectivity. The purpose of these efforts is to illuminate the general mechanisms used by Nature to achieve molecular shape-selectivity, and to provide new synthetic receptors that can be used in separation technologies, drug delivery. or as the basis of new catalytic processes. Recent progress toward this objective is reviewed.