Title: Multifractal analysis: A mathematical tool for signal classification Abstract. Multifractal analysis uses families of parameters that allow to classify signals or images. These parameters are based on function spaces regularity indices; initially the spaces used were Sobolev or Besov spaces. New scales have recently been shown to be more relevant for that purpose. They are defined by conditions on the walelet decomposition of the signal. We will describe properties of these ``oscillation spaces''. Applications will focus on the study of fully developed turbulence: Statistical tests based on these criteria allow to discriminate between several classical turbulence models which, up to now, could not be retained or discarded on the basis of physics criteria. Applications to other types of signals or images will also be presented.