This book concerns the institutionalisation of the physical sciences. The book breaks with the established tradition in the history, philosophy and sociology of sciences by attempting to capture both the cognitive and social dimensions of institutionalisation in one unified analysis. This unifica tion has been achieved through a treatment of research as goal directed social action - a theme which has been developed both theoretically and empirically. The analysis presented is therefore unique in its breadth of focus and shows how the traditional concerns of sociology with generalised macro-structures of meaning and action can be related to the lifeworlds of individual scientists. The sociology of the sciences is still today a relative newcomer to the field of sciences studies which has traditionally been dominated by the history and philosophy of the sciences. I hope that this book reflects the excitement I experienced in being able to respond to the debates and concepts which erupted in that particularly fertile period follOwing the publication of Kuhn's Structure of Scientific Revolutions in 1962 - a period from which a cogni tively oriented sociology of the sciences was to emerge as a serious challenger to orthodoxies in the history, philosophy and sociology of sciences.