This paper discusses the surface order-dependent adsorptive activity at the surfaces of tetrahedrally coordinated semiconductors. It stresses the differences between elemental (e.g., Si) and compound materials (e.g., Gas, CdS, and ZnO) as well as the differences between ordered and disordered nonpolar compound semiconductor surfaces. Several examples will be presented that compare oxygen adsorption on ordered and disordered surfaces. It will be shown that adsorption on ordered nonpolar compound semiconductor surfaces is weak in comparison to adsorption on ordered elemental semiconductor surfaces, that among the compound semiconductors the ordered nonpolar surfaces of the II-VI materials (e.g.,) are much weaker adsorbents than the similar surfaces of the III-V materials (e.g., GaAs), and that adsorption on nonpolar compound semiconductor surfaces is much enhanced by surface disorder. It will be argued that these phenomena can collectively be attributed to bonding ionicity. Finally, an attempt will be made to establish a connection between the order/disorder phenomena described here and the collective electronic and active site models of surfaceactive catalysis.