This study examined empirical research on shyness, inhibition, and social withdrawal published in "Child Development,""Developmental Psychology," and "Development and Psychopathology" between 1990 and 1996, focusing on: (1) conceptual definitions; (2) operational definitions; (3) agreement between conceptual and operational definitions within studies; and (4) agreement across studies. The sample was comprised of 32 articles whose titles included shy(ness), inhibit(ion), or withdraw(al); they were located through a CD-ROM PsycLIT search. Conceptual definitions and individual components of the operational definitions were categorized. Results indicated that withdrawal was not well-defined operationally or conceptually; only four studies (33 percent) included conceptual definitions and there was little inter-study agreement. Forty-two percent of the operational definitions included items not fitting the conceptual definition. Inhibition was more consistently defined conceptually and operationally. Seventy-five percent of the inhibition studies specified conceptual definitions, and there was considerable inter-study agreement. Fifty-six percent included a temperamental component. No study included measures inconsistent with the conceptual definition. Only two studies used the term shyness and neither specified a conceptual definition. Overall, withdrawal was a nebulous construct and often seemed to serve as a "catch-all" category for various types of internalizing problems. The inhibition construct was relatively clear and distinct. The lack of clarity regarding withdrawal implies that its literature should not be taken at face value. (The 33 studies reviewed are listed. An appendix outlines the operational definition components. Two figures graphically display findings. Contains nine references.) (KDFB)