Recent trends in the development of analytical procedures are directed toward platforms and devices that are speedy, small, sensitive, and specific. However, these aims may require new reagents and approaches that are tailor-made for the application envisaged, or re-tooling of existing systems. Whichever approach is taken, the problems and demands remain similar. They include non-specific binding and its elimination, oriented immobilization of ligands and other molecules, matrix effects, the need for sample "clean-up," single or multiple use, miniaturization, microfluidic needs, ease-of-use, user, legislator and consumer appreciation, acceptance and requirements, and cost considerations. These and other issues will be critically analyzed in the light of recent achievements and the potential to overcome current obstacles will be discussed. © Taylor & Francis Group, LLC.