This publication is a collection of papers presented at a technical symposium on R-curves held during the regular Committee E24 meetings in the Fall of 1971. It represents an early effort by a Subcommittee 1 task group to organize the present state of R-curve technology in preparation for a renewed attempt to apply the method to plane-stress fracture toughness evaluation. The symposium was sponsored by Committee E24 on Fracture Testing of Metals, American Society for Testing and Materials. D. E. McCabe, Armco Steel Corp., presided as symposium chairman.