In integrated conservation and development projects (ICADPs), the development component is a means to the end of conserving biodiversity and maintaining ecosystem functioning. This paper discussed the ecological, economic and social challenges to implementing ICADPs in Papua New Guinea. Concentrating particularly on economic constraints, the author noted that the viability of local enterprises based on sustainable use of forests was hindered by poor infrastructure and the high cost of inputs, especially in comparison to the alternative of commercial logging. The author suggested that individual ICADPs should acknowledge the necessary complexity, slow pace and site-specificity of project development.