After an extended solar minimum, a significant increase in the solar activity starting late in 2009 has provided several Solar Energetic Particle (SEP) events observable from spacecraft widely separated in longitude. We analyze the August 18, 2010 SEP event, originating from active region 11099, near the west solar limb. Electrons and ions accelerated during this event were clearly observed by both STEREO spacecraft, separated by more than 152 degrees, as well as by near-Earth spacecraft. The large intensity increase permits the study of time profiles and anisotropies measured at three different locations with good statistical accuracy. We combine multi-spacecraft in-situ and remote-sensing observations with a three-dimensional particle propagation model in order to clarify the physical processes responsible for the large angular spread of the energetic particles.