Abstract: Process and apparatus are disclosed for jettexturing yarn of continuous filaments to increase the bulk. Thermoplastic filaments are crimped by forwarding the yarn in a jetted stream of hot compressible fluid, such as heated air or steam onto a moving screen or other foraminous surface and cooling the yarn on the surface prior to imposing any substantial tension on the filaments. Products having especially desirable properties are obtained by treating filaments which develop crimp due to differential shrinkage properties when heat-relaxed, e.g., bicomponent filaments or meltspun filaments which have been quenched asymmetrically by directing cold fluid across the spinneret face.