This paper assesses the extent of structural similarity or isomorphism among nonprofit organizations in Australia. Based on neo-institutional theory, the paper explains such isomorphism in terms of these organizations' subordination and dependency, the uncertainties they face, and the networks of experts of which they are a part. The analysis uses the nonprofit component of a 2001-2002 random sample of Australian employment organizations. It finds surprisingly little isomorphism in this subsample and few differences in isomorphism according to the level of the factors thought to produce similarity. The discussion of the findings focuses on the suitability of the nonprofit sector as the appropriate organizational field within which isomorphism involving these organizations is likely to be produced. Industries, which include all organizations that produce the same product or service, be they nonprofit, for-profit, or government, may be more appropriate interactional fields for the development of isomorphism.