The present review paper deals with the development of catalytic systems in water in the presence of micelles obtained by addition of surfactants, focusing on the effects of these simple, economic, and green reaction media on important aspects like recyclability, activity, product and substrate selectivity. Contributions from 2005 to 2014 are surveyed with particular emphasis on emerging findings and directions in the field of catalysis. Surfactants enable formation of nanosized apolar aggregates in bulk water where the catalysts and reagents can be dissolved thanks to weak intermolecular interactions like the hydrophobic effect and ion pairing operating in a more concentrated system compared to the bulk solvent. While in the past the use of surfactants was a straightforward approach to enable solubilization of reaction mixtures in water, nowadays specific interactions between substrates, catalysts and micelles are investigated by means of NMR and other techniques to better understand the molecular basis of this kind of supramolecular catalysis. Specifically designed surfactants to engineer micelles in order to compete efficiently with traditional catalysis in organic solvents are nowadays available.