David Bostock presents a critical appraisal of Bertrand Russell's philosophy from 1900 to 1924--a period that is considered to be the most important in his career. Russell developed his theory of logic from 1900 to 1910, and over those years wrote the famous work Principia Mathematica with A. N. Whitehead. Bostock explores Russell's development of 'logical atomism', which applies this logic to problems in the theory of knowledge and in metaphysics, and was central to his philosophical work from 1910 to 1924. This book is the first to focus on this important period of Russell's development, examining the three key areas of logic and mathematics, knowledge, and metaphysics, and demonstrating the enduring value of his work in these areas.