Four-arm dipmeter logs from six wells and a Formation MicroScanner (FMS) image log from one well in the southern Bonaparte Basin were interpreted for in situ stress indicators. Results of the analysis reveal a consistent NE-SW in situ maximum horizontal stress (&sgr;Hmax) orientation (055 ¿N). This orientation is parallel to the average &sgr;Hmax determined in the northern Bonaparte Basin, the onshore Canning Basin, and in New Guinea. The data support the interpretation that the NE-SW &sgr;Hmax orientation in the area reflects a first-order stress pattern controlled by plate boundary forces along the northeastern margin of the Indo-Australian Plate (IAP) and contradict the suggestion that NE-SW &sgr;Hmax in the northern Bonaparte Basin is a second-order effect associated with boundary induced flexural stresses. Numerical modeling suggests that the divergence of &sgr;Hmax from an orientation parallel to plate motion can be explained by the heterogeneous nature of the northeastern boundary of the IAP. ¿ 2000 American Geophysical Union