The spread of behavior over social networks depends on the contact structure among individuals, and seeding the most influential agents can substantially enhance the extent of the spread. While the choice of the best seed set, known as influence maximization, is a computationally hard problem, many computationally efficient algorithms have been proposed to approximate the optimal seed sets with provable guarantees. Most of the previous work on influence maximization assumes the knowledge of the entire network graph. However, in practice, obtaining full knowledge of the network structure is very costly.In this work, we consider the choice of k initial seeds to maximize the expected number of adopters under the independent cascade model. We propose a "probe-and-seed" algorithm that provides almost tight approximation guarantees usingÕ(pn 2 + √ pn 1.5 ) edge queries inÕ(pn 2 + √ pn 1.5 ) time, where n is the network size and p is the probability of spreading through an edge. To the best of our knowledge, this is the first result to provide approximation guarantees for influence maximization, using a sub-quadratic number of queries for polynomially small p. We complement this result by showing that it is impossible to approximate the problem using o(n 2 ) edge queries for constant p. In the end, we consider a more advanced query model, where one seeds a node and observes the resultant adopters after running the spreading process. We provide an algorithm that uses onlyÕ(k 2 ) such queries and provides almost tight approximation guarantees.1 1 INTRODUCTION Decision-makers in marketing, public health, development, and other fields often have a limited budget for interventions, such that they can only target a small number of people for the intervention. Thus, in the presence of social or biological contagion, they strategize about where in a network to intervene -often where to seed a behavior (e.g., product adoption) by engaging in an intervention (e.g., giving a free product). The influence maximization literature is devoted to the study of algorithms for finding a set of k seeds so as to maximize the expected adoption, given a known network and a model of how individuals are affected by the intervention and others' adoptions [15]. However, finding the best k seeds for many models of social influence is NP-hard, as shown by Kempe, Kleinberg and Tardos [21]. Much of the subsequent influence maximization literature is concerned with developing efficient approximation algorithms with theoretical guarantees to make use of desirable properties of the influence function such as submodularity [10,34].With few exceptions [28,36], the seeding strategies that are studied in the influence maximization literature require explicit and complete knowledge of the network. However, collecting the entire network connection data can be difficult, costly, or impossible. For example, in development economics, public health, and education, data about network connections is often acquired through costly surveys (e.g., [4,7,8,30]). Indeed, t...