This letter addresses the problem of localization in a quasi-synchronous network using time-of-arrival (TOA) measurements. The object to be localized is passive, i.e., it is neither a transmitter nor a receiver. Unlike prior TOA-based algorithms, no perfect synchronization between the transceivers is assumed here. A two-step linear algorithm is proposed to jointly estimate the location of the passive object and the unknown time offset between the transceivers. The Bayesian Cramer-Rao lower bound (BCRB) for quasi-synchronous networks is then given for comparison. It is shown that the proposed algorithm can achieve the BCRB and significantly outperform the algorithms using time-difference-of-arrival (TDOA) and differential TOA (DTOA) measurements. © 2014 IEEE.