As blog community is growing rapidly, the effect of digital network acquired through blog on users’ social interactions has become an important issue. The rapid diffusion of the blog can be attributed to its role in building social networks among bloggers through exchange of information and expression of feelings and opinions. The network acquired through blogging can have a dramatic effect on a person’s social activities and interactions. If we are to understand fully the blog’s ripple effect in the social activities, we should conduct our analysis at the level of bloggers’ relationships, in addition to those at the level of the individual bloggers or at the entire community level. Findings on the process of initiating, maintaining and terminating the relationships among bloggers will provide in depth understanding on the social impacts of blog. Moreover, the relational behavior of individual bloggers should be closely related to their network structure in the blogosphere because structure and behavior were found to interact intimately. Therefore, it is necessary to understand the interplay between the structural properties of the social networks and relational behaviors of bloggers who belong to that network. Since blogging is a rather recent phenomena, few studies have addressed the relational behaviors by which relationships are established and maintained in the blogosphere, or the interaction of these behaviors with the structure of the blogosphere’s social network. Lack of these studies would undermine our understanding on the blogging phenomena because social value caused by relational behavior and network structure is an important factor to determine the weblog success. The primary goals of this research are to identify the relational behaviors of bloggers, and to investigate how these behaviors interrelate with the structures of the social networks formed within the network of the blog. We conducted a social network survey, as well as in-depth interviews, with thirty-eight active bloggers. We performed a quantitative analysis of the survey data to identify major types of social network structure. The interview data was analyzed qualitatively, using a grounded theory approach, to identify critical categories of relational behaviors. Based on the results, we have posited four distinct social network structures, each formed by compositions of four distinct types of relational behaviors.