The tensile properties of wet webs are affected by various pulping and papermaking treatments in a complex manner. It is shown that there are two main factors that are in control. One is the extent of fibre-fibre interaction, and the other is the presence of curl and microcompressions in the fibres. Increased fibre flexibility, collapse, fibrillation and fines improve fibre- fibre interaction and thus enhance both wet-web tensile strength and stretch. Fibre curl increases wet-web stretch at low solids whereas the presence of microcompressions improves stretch at high solids. The mechanism by which curl and microcompressions control wet-web stretch are discussed. Thus, while an increase in the degree of curl and microcompression increases potential stretch, the extent to which this potential is realized is controlled by the extent of fibre-fibre interaction.