In this chapter I review empirical studies directly testing the hypotheses of my 1973 paper " The Strength of Weak Ties" (hereafter "SWT") and work that elaborates those hy- potheses theoretically or uses them to suggest new empirical research not discussed in my original formulation. Along the way, I will reconsider various aspects of the theoretical argument, attempt to plug some holes, and broaden its base. T H E STRENGTH O F WEAK TIES: A NETWORK THEORY REVISITED Mark Granovetter STATE UNIVERSITY O F N E W YORK, STONY BROOK The Argument Recapitulated T h e argument asserts that our acquaintances (weak ties)are less likely to be socially involved with one another than are our close friends (strong ties).Thus the set of people made u p of any individual I a m indebted to Everett Rogers who first suggested this study, inviting it for a special session of the International Communications Association meet- ings on the weak-ties hypothesis. T h e first version was delivered at this session in Acapulco on May 21, 1980. A version closer to the present one was delivered at the conference on Structural Analysis, April 4, 1981, SUNY-Albany. I a m indebted to participants in these two conferences for their generous comments- especially Fernando Morett, Scott Feld, Nan Lin, and Ronald Rice. This chapter has also drawn heavily from the comments and literature review of Ellen Granovetter. [Sociological Theory, Volume 1 (1983), 201-233.]

202 Sociological Theory and his or her acquaintances comprises a low-density network (one in which many of the possible relational lines are absent) whereas the set consisting of the same individual and his or her close friends will be densely knit (many of the possible lines are present). T h e overall social structural picture suggested by this argument can be seen by considering the situation of some arbitrarily selected individual- call him Ego. Ego will have a collection of close friends, most of whom are in touch with one another- a densely knit clump of social structure. Moreover, Ego will have a collection of acquaintances, few of whom know one another. Each of these acquaintances, however, is likely to have close friends in his own right and therefore to be enmeshed in a closely knit clump of social structure, but one different from Ego's. The weak tie between Ego and his acquaintance, therefore, becomes not merely a trivial acquaintance tie but rather a crucial bridge between the two densely knit clumps of close friends. T o the extent that the assertion of the previous paragraph is correct, these clumps would not, in fact, be connected to one another at all were it not for the existence of weak ties (SWT, p. 1363). It follows, then, that individuals with few weak ties will be deprived of information from distant parts of the social system and will be confined to the provincial news and views of their close friends. This deprivation will not only insulate them from the latest ideas and fashions but may put them in a disadvantaged position in the labor market, where advancement can depend, as I have documented else- where (1974), on knowing about appropriate job openings at just the right time. Furthermore, such individuals may be difficult to organize or integrate into political movements of any kind, since membership in movements or goal-oriented organizations typically results from being recruited by friends. While members of one or two cliques may be efficiently recruited, the problem is that, without weak ties, any momentum generated in this way does not spread beyond the clique. As a result, most of the population will be untouched. T h e macroscopic side of this communications argument is that social systems lacking in weak ties will be fragmented and incoherent. New ideas will spread slowly, scientific endeavors will be handicapped, and subgroups separated by race, ethnicity, geography, or other characteristics will have difficulty reaching a modus vivendi. These

Strength of Weak Ties 203 themes are all taken u p in greater detail, with supporting evidence, in SWT. I now wish to review the past eight years' literature on weak ties. First, I will review work focusing on the impact of weak ties on indi- viduals, then work relating to the flow of ideas and the sociology of science, and, finally, work evaluating the role of weak ties in affecting cohesion in complex social systems. The Impact of Weak Ties on Individuals An early draft of SWT was entitled "Alienation Reconsidered: T h e Strength of Weak Ties." In this draft I argued that weak ties, far from creating alienation, as one might conclude from the Chicago school of urban sociology-especially from Louis Wirth-are actually vital for an individual's integration into modern society. Upon further reflection it is clear that this argument is closely related to certain classic themes in sociology. In the evolution of social systems, perhaps the most important source of weak ties is the division of labor, since increasing specialization and interdependence result in a wide variety of specialized role relationships in which one knows only a small seg- ment of the other's personality. (See the perceptive comments of Sim- mel, 1950, pp. 317-329.) In contrast to the emphasis of Wirth, and also Toennies, that role segmentation results in alienation, is the Durkheim- ian view that the exposure to a wide variety of different viewpoints and activities is the essential prerequisite for the social construction of individualism. In a provocative article, Rose Coser (1975) takes u p some of these themes. She describes the complexity of role set-to use Robert Mer- ton's expression for the plurality of others with whom one has role relations-as a "seedbed of individual autonomy." In Simmel's view, she recalls, "the fact that an individual can live u p to expectations of several others in different places and at different times makes it possible to preserve an inner core, to withhold inner attitudes while conforming to various expectations" (p. 241). Furthermore, persons "deeply enmeshed in a Gemeinschaft may never become aware of the fact that their lives do not actually depend on what happens within the group but on forces far beyond their perception and hence beyond their con- trol. T h e Gemeinschaft may prevent individuals from articulating

204 Sociological Theory their roles in relation to the complexities of the outside world. Indeed, there may be a distinct weakness i n strong ties" (p. 242). Coser then elaborates the cognitive ramifications of this conun- drum: "In a Gemeinschaft everyone knows fairly well why people behave in a certain way. Little effort has to be made to gauge the intention of the other person. . . . If this reasoning is correct . . . the manner of communication will tend to be different in a Gesellschaft. Hence, the type of speech people use should differ in these two types of structures" (p. 254). She relates this difference to Basil Bernstein's dis- tinction between restricted and elaborated codes of communication. Restricted codes are simpler- more meanings are implicit and taken for granted as the speakers are so familiar with one another. Elaborated codes are complex and universal-more reflection is needed in organiz- ing one's communication "when there is more difference between those to whom the speech is addressed" (p. 256). While some weak ties may connect individuals who are quite similar, of course, there is, as I pointed out in SWT, "empirical evidence that the stronger the tie connecting two individuals, the more similar they are, in various ways" (p. 1362). Thus Coser's argument applies directly to the distribu- tion of weak and strong ties. She concludes that in "elaborated speech there is a relatively high level of individualism, for it results from the ability to put oneself in imagination in the position of each role partner in relation to all others, including oneself" (p. 257). She goes on to argue that the social structure faced by children of lower socio- economic backgrounds does not encourage the complex role set that would, in turn, facilitate the development of "intellectual flexibility and self-direction" (p. 258). This discussion casts a different light on some of the arguments of SWT. There I argued that while West Enders, for example, did have some weak ties, they were embedded within each individual's existing set of strong ties rather than bridging to other groups. I interpreted this lack of bridging as inhibiting organization because it led to overall fragmentation and distrust of leaders. Coser's argument suggests further that bridging weak ties, since they do link different groups, are far more likely than other weak ties to connect individuals who are significantly different from one another. Thus, in addition to the over- all macrostructural effect of bridging weak ties, I could also have argued that they are exactly the sort of ties that lead to complex role sets

Strength of Weak Ties 205 and the need for cognitive flexibility. T h e absence of flexibility may have inhibited organization against urban renewal, since the ability to function in complex voluntary organizations may depend on a habit of mind that permits one to assess the needs, motives, and actions of a great variety of different people simultaneously. There is no special reason why such an argument should apply only to lower socioeconomic groups it should be equally persuasive for any set of people whose outlook is unusually provincial as the result of homogeneous contacts. In American society there is thus some reason for suggesting that upper-class individuals as well as lower-class people may suffer a lack of cognitive flexibility. Baltzell (1958) and others have described in detail the cloistered features of upper-class interaction Halberstam (1972) has suggested that such a social struc- ture creates inflexibility in the form of arrogance and a sense of infalli- bility and had much to do with American involvement in the Vietnam War. At a more mundane level, I argued (SWT, pp. 1369-1373 1974, pp. 51-62) that weak ties have a special role in a person's opportunity for mobility- that there is a "structural tendency for those to whom one is only weakly tied to have better access to job information one does not already have. Acquaintances, as compared to close friends, are more prone to move in different circles than oneself. Those to whom one is closest are likely to have the greatest overlap in contact with those one already knows, so that the information to which they are privy is likely to be much the same as that which one already has" (1974, pp. 52-53). In my empirical study of recent job changers (1974), I found, in fact, that if weak ties are defined by infrequent contact around the time when information about a new job was obtained, then professional, technical, and managerial workers were more likely to hear about new jobs through weak ties (27.8 percent) than through strong ones (16.7 percent), with a majority in between (55.6 percent). Three pieces of empirical research offer partial confirmation of this argument. Langlois (1977) studied a large sample of men and women in a branch of the Quebec provincial government. Langlois notes that even though this branch had "attempted to formalize the recruitment of its members as much as possible" (p. 217), 42.7 percent of the 2,553 individuals in the sample found their jobs through per- sonal contacts. Using frequency of recent contact as the definition of tie