These proceedings contain the papers presented at the 4th International S- posium on Location and Context Awareness (LoCA) during May 7-8, 2009 in Tokyo, Japan.Locationandcontextawarenessarefundamentstonext-generation mobile and pervasive computing systems. Pervasive computing is a model of computing in which computation is everywhere and computer functions are - tegrated into everything. The ultimate aim is to make information, applications and services available anywhere and at anytime in the human environment in a ?uid manner appropriate to our current context. Once away from the desktop,...