This reply addresses the issues raised in Jackson's (1986) comment on Mullen's (1985a) meta-analysis of the effects of strength and immediacy in group contexts. It is reasoned that the conceptual analysis of social impact theory is unflattering but accurate, that the categorization scheme used in the metaanalysis is straightforward and defensible, and that the inclusion criteria for the meta-analysis provided the opportunity for an unbiased, stringent test of Social Impact Theory's unique treatment of strength and immediacy in group contexts. Despite Jackson's comments, the results of the meta-analytic review call into question the effects of strength and immediacy in group contexts, and thereby (pending further evidence) Social Impact Theory itself. Mullen (1985a) recently reported the results of a meta-analysis of the effects of the two elements of Social Impact Theory (Latane, 1981) which have received the least attention: source strength and source immediacy. This meta-analysis revealed that the effects of source strength and source immediacy in group contexts are rather weak and inconsistent, and may very well be the result of methodological artifacts. Rising to the defense of Social Impact Theory, Jackson (1986) has criticized three aspects of Mullen's meta-analysis: (a) the description of Social Impact Theory presented in Mullen's article; (b) the categorization scheme used to account for the inconsistency in the effects of source strength and source immediacy; and (c) the criteria used to select studies for inclusion into the meta-analysis. These criticisms do not further our understanding of the effects of source strength and immediacy in group contexts, and can be dismissed summarily.