The existence and development of the scientific discipline now known as plasma physics owe much to its interaction with astrophysics. Many of the concepts of plasma physics were first discussed i n an astrophysical setting by Alfvén, Chapman, Cowling, Fermi and Spitzer. Within the last twenty years, there has been a tremendous increase – both in scope and in detail – in our understanding of the plasma state and in our knowledge of the astrophysical world. Although astronomers provide a wealth of significant problems, and plasma physicists provide a battery of powerful concepts and theories, the great opportunity of bringing plasma theories to bear upon astronomical problems has not been fully exploited. It was in recognition of this situation that a four day conference was held in October 1968 at Asilomar, California, to bring together three different groups of people: plasma physicists, astronomers and theoretical astrophysicists. To reduce the amount of material to be covered at the conference, discussion was confined to the role of plasma instabilities in astrophysics.