Orthogonal frequency division multiple access (OFDMA) has a major role in the evolution of broadband wireless networks. It enables efficient transmission of a wide variety of data traffic by optimizing power, subcarrier, or bit allocation among different users. Secrecy or private information communications to mobile users are often needed in present and future wireless systems. Hence, it is essential to consider the security demand in radio resource allocation of OFDMA networks. This chapter presents an overview of resource allocation techniques in OFDMA-based wireless networks for providing physical layer security. In particular, a general framework of power and subcarrier allocation in OFDMA downlink networks where users requiring secrecy and nonsecrecy messages coexist is introduced in detail. Through theoretical analysis, several insights into resource allocation with secrecy requirement are provided. At last, possible directions for future research are also given.