Electromagnetic probes are ideally suited to investigate hot and dense matter produced in high energy heavy ion collisions. They do not undergo strong interactions, leave undisturbed by the surrounding medium and thus probe the full time evolution of the collision. The dielectron continuum is rich in physics. Dalitz decays of light hadrons and direct decays of vector mesons, which might be modified in the medium, hard processes, such as correlated charm production contribute to the spectrum. Although correlated e+e- pairs are rare, the large statistics collected by PHENIX for Au+Au collisions at sqrt(s_NN)= 200 GeV provides a significant sample to investigate the dilepton continuum. The continuum and its resonances are separated from the combinatorial background via an event mixing technique. Mass and transverse momentum spectra are presented and compared with the expectations from decays of hadronic sources. System size dependency can be studied by comparing different centrality bins.