The present chapter featured the concept of ascribed epistemic authority (Kruglanski, 1989) offered as a unique perspective on source effects in social judgment. In contrast to prior approaches that viewed the source of communication as external to the self, the present framework assumes that both the self and external sources may be assigned different degrees of epistemic authority in different domains and that such assignment affects various aspects of individuals' information-processing activities, including the search for information and the readiness to base decisions on the information given. The present framework claims a central role for the information's source in suggesting that an evaluation of its epistemic authority (however implicit) constitutes an essential preliminary phase in individuals' approach to information. For instance, a careful processing of a persuasive message may occur only after a prior determination has yielded that one possesses a sufficient epistemic authority to make sense of the message and hence is not dependent on an external source for interpretation. In general, it could be the perceived gap in epistemic authority ascribed to oneself versus an external source that determines the source's influence. A failure to take one's self-ascribed epistemic authority into account might thus lead to inaccurate estimations of the potential impact of external sources' authority. A source with relatively high ascribed authority may be quite persuasive with respect to a recipient of much lower self-ascribed authority, but much less persuasive with respect to a recipient of a high self-ascribed authority. We thus conceive of epistemic authority ascriptions as meta-cognitive beliefs about a source of information. This perspective highlights the developmental, individual differences, self-related, and applied aspects of source phenomena. The developmental aspect pertains to the fact that in the course of "growing up," the initial generalized epistemic authority accorded by the child to its adult caregivers is gradually distributed over a variety of sources in the individual's environment, including the self. The individual difference aspect pertains to the fact that individuals' disparate socialization histories may foster the development of correspondingly different hierarchies of epistemic authorities for different individuals. In turn, these may effect behavioral differences in the search for and reliance on information for decision making and action. The self-relevant aspect relates to the role of experience in attitude and opinion formation and the moderating role that self-ascribed epistemic authority may play in one's ability to draw strong conclusions from experience. Finally, the applied aspect pertains to the fact that identification of a distributional pattern of epistemic authorities assigned by a specific group of individuals to specific sources in specific real-world contexts (in politics, education, and health domain, among others) may allow one to make specific predictions and plan specific interventions designed to influence those individuals in a desirable direction. For instance, Internet-savvy, educated consumers may weigh heavily their own epistemic authority in health-related domains and expend considerable efforts on analyzing information relevant to their condition before opting for a course of treatment. By contrast, persons with low self-ascribed authority may be guided primarily by their family physician's recommendations in all medical matters. The unfolding historical trends in these regards, and their impact on physicians' and patients relations, could be of considerable real-world interest. Research conducted in the epistemic authority paradigm supported various aspects of the foregoing analysis with respect to the developmental, individual difference, self-related, and applied aspects of source effects. Yet a great deal of further work is needed to fully understand the development and functioning of epistemic authority in social judgment. As already noted, the relation of epistemic authority ascriptions to attachment patterns (Mikulincer & Shaver, in press) suggests intriguing questions: Would secure attachment to one's parents contribute to a generalized trust in others and hence to the development of a strong emphasis on external epistemic authorities, and would it mean a retardation in the development of one's self as an epistemic authority? Or would this contribute, instead, to a more nuanced differentiation of epistemic authorities, with the self being ascribed authority in specific domains and others being conceded authority in other domains? Similarly, would an avoidant attachment style contribute to the development of an exaggerated and overgeneralized sense of epistemic authority, and the tendency of excessive self-reliance in domains where one's objective epistemic competence may be limited? These questions and others may be fruitfully pursued in future research contributing to the integration of attachment and social influence theories. A different set of issues may arise in research on the situational determinants of epistemic authority ascriptions. Social cognition researchers have been emphasizing how people's attitudes, judgments, and beliefs may be situationally constructed (cf. Bem, 1972; Kruglanski & Stroebe, in press). Insofar as epistemic authority ascriptions also constitute beliefs, they too should be susceptible to various situational influences. In this vein, Brinol and Petty (2004) review evidence attesting that various experimental manipulations may affect individuals' confidence in their cognitive responses to a communication topic, and hence, presumably, their self-ascribed epistemic authority in a domain. It would be of interest to investigate whether similar effects may be obtained in regard to external sources as well. For example, nodding one's head, an assured tone of voice, the use of definite and unqualified terminology, or the speed of speech (Miller, Maruyama, Beaber, & Valone, 1976) may convey a source's confidence, leading to an ascription of a high epistemic authority and enhancing the source's persuasive impact upon a recipient. Furthermore, whereas the situational manipulations of confidence reviewed thus far pertained to possible informational effects on epistemic authority, it is likely that various motivations would exert such effects as well. In this vein, Bar (1999) reported that participants' need for cognitive closure effected more extreme assignments of epistemic authority, such that the high-authority sources were accorded an even higher authority by individuals high (vs. low) on the need for cognitive closure. Conversely, low-authority sources were accorded an even lower authority by high (vs. low)-need-for-closure individuals. Whereas Bar's findings were based on a dispositional need for closure assessed by means of a scale (Webster & Kruglanski, 1994), it should be the case that situational inducements of such a need, e.g., via noise, fatigue, or time pressure, should also affect an increased differentiation in epistemic authority assignments. In addition to nondirectional motivational effects (such as the need for closure effects described above), it is also likely that various directional motivations (Kunda, 1990; Kruglanski, 1996) would similarly exert an impact on epistemic authority assignments to self and others. For instance, in a situation where ascribing epistemic authority to a source would seem highly desirable, e.g., where the source was in a leadership position or where one was informationally dependent on the source for important outcomes, one might assign the source a greater epistemic authority than one would in other circumstances. These possibilities and many others could be profitably explored in subsequent research conducted within the epistemic authority framework.