This paper proposes a soft switching interleaved Boost-Flyback converter employed as a preregulator stage providing power factor correction. The use of a soft commutation cell allows the main switches to be turned on and off under null current and null voltage conditions, respectively. Interleaving techniques imply the overall reduction of the Boost inductor size and also the minimization of the switching losses without increasing voltage and current stresses. This topology has the advantages of the Flyback converter, as auxiliary power supplies are not necessary. A theoretical analysis, including the description of the operating stages and relevant expressions is developed. Additionally, simulation and experimental results are presented.