Linear alkylbenzene sulfonate (LAS) is the world's largest volume surfactant. During industrial processing it is transformed from a 'sticky', yellow material of relatively low viscosity into a 'springy', white, high-viscosity substance suitable for use in washing powder. It is demonstrated that this transition can be achieved by moderate shear alone at 25degreesC and is accompanied by a phase transition from a planar lamellar structure to one consisting of multi-lamellar vesicles (MLVs). At higher shear rates the MLVs are not formed, the lamellar structure is stable and oriented in the direction of the flow; this is accompanied by the macroscopic properties of untreated LAS. At 60degreesC it is not possible to achieve the phase transition to MLVs, nor to obtain the 'springy' white material by shear alone. Under all conditions the inter-lamellar spacing of the bulk is around 30 Angstrom, but an approximately 34 Angstrom lamellar phase, oriented parallel to the wall, was always observed (even when MLVs were formed in the bulk) close to the walls of the capillary in which shearing occurred.