In many sensor network applications, the localization of an emitting acoustic source as well as those of sensor nodes is of importance. In this poster, we first tackle the localization of the acoustic source by utilizing the Approximate-Maximum-Likelihood (AML) methodology. By using the virtual array method, the AML estimated direction-of-arrival (DOA) can be used to localize the source under controlled reverberant scenarios. For localization of an impulsive source, whitening of the observed data before the AML operation has been shown to be an effective operation. For wireless sensor node localization, we assume the locations of the anchor nodes are known. Range information among neighborhood sensor nodes as well as from sensor nodes to neighborhood anchor nodes are also available. By using the distributed Gauss-Newton estimation approach, a sequential algorithm and a parallel algorithm are shown to be efficient in determining the locations of the sensor nodes.