In this chapter, we present several authentication methods that have been proposed for WMNs. These authentication methods can be classified into three different types. First, the PSK authentication methods rely on a shared secret between two STAs or between an STA and an AS. In the first case, STA has to store a password or a PSK for each of its peer STAs, while in the second case STA has to pass through the AS each time it authenticates to another STA. The second type of authentication is the certificate-based authentication. It relies on the use of certificates and requires the heavy deployment of a public key infrastructure (PKI) that is controlled by a CA. In general, the management of certificates in wireless environments is a cumbersome task because it requires the definition of a certificate management policy to control the generation, transmission, and revocation of certificates. That is, the network STAs will have to periodically download a certificate revocation list (CRL) in order to update their local lists of revoked certificates and expired keys. However, the CRL request and response messages are bandwidth consuming. Finally, the third type of authentication relies on IBC. IBC seems to be a well-suited solution for authentication issues related to WMN. Indeed, IBC permits the use of public key cryptography with no need for certificates and PKI deployment, as keys are directly derived from nodes identities. However, IBC algorithms, especially those relying on pairing functions, are less efficient in terms of time compared to classical encryption and signature algorithms (e.g., DES, AES, RSA, ECDSA, ElGamal).