The interaction of small polyelectrolytes or oligoions with surfactants appears to follow a model that we have recently established for large polyelectrolytes but the smaller systems offer better control and allow us to explore the specific interactions that underlie the behaviour of these mixtures. We are currently investigating the effects of size, branching and variable charge in amine/SDS systems, which is leading to clear information about branching effects and about the nature of the head group interactions. Oligo-arene sulphonates, already studied by conventional methods, offer control of the charge separation on the oligomer as a parameter and the measurements suggest some defects in our present model. The information that is the key to understanding and characterizing these systems properly is direct observation of the surface by neutron reflectometry.