The reason why there are at least 6 distinct high affinity IGFBPs is obviously a great challenge for investigators to unravel. In order to undertake this challenge a wide range of techniques have now been developed for investigating IGFBPs. As the IGFBPs have been characterized it has become clear that they are complex multi-faceted molecules; the more tools that can be applied to examine them, the better are the chances for getting a complete picture. The return for the investment of all this technology is the hope that elucidation of the sophisticated system of IGFBPs will provide a much better understanding of how the pluripotential actions of the ubiquitous IGFs can be most appropriately regulated in a manner specific to each tissue and according to developmental and environmental conditions.