The combination of projectile fragmentation reactions and in-flight separation has proved to be a powerful tool to produce nuclei at the limits of stability. Decay studies of very neutron-deficient projectile fragments led to the discovery of several new &bgr;-delayed particle emitters. Basic principles of the method are described and various aspects of extracting interesting spectroscopic information from &bgr;-delayed particle studies at projectile fragment separators are discussed. ©2000 American Institute of Physics.