ASCOS IV is an astrophysics & cosmology student conference, whose main objective is to allow graduate students to meet and interact with each other. This will be a one-day conference at the faculty of physics at Weizmann institute at Rehovot, and all Ph.D. and M.Sc. astrophysics/cosmology students are invited to register and submit an abstract. The conference will consist of a series of talks, with preference to as wide a representation of topics and/or universities as possible, as well as a poster competition, and plenty of time for discussions and interactions between students from different universities.