A field of research that began with a curious observation in Drosophila has resulted in a new understanding of how cells respond to sudden and adverse changes in their environment. In addition through the study of the structure/function of the stress proteins, especially those which function as molecular chaperones, new insights into the details by which proteins are synthesized and acquire their final biologically active conformation have been realized. Equally exciting is the progress being made as it relates the potential diagnostic and therapeutic applications of the stress-response proteins. The use of stress proteins as the next generation of vaccines and/or their use as potentially powerful adjuvants, capable of stimulating both T and B cell responses to a particular antigen of interest appear close to becoming a reality. One wonders how many more surprises are in store for us as we continue to explore this evolutionally conserved cellular stress response.