Paul Bogaard discusses Whitehead’s ‘philosophy of evolution’, tracing the concepts of organism, environment and evolution through the Harvard lectures and his published works, concluding that ‘evolution’ as a concept seems to fade in importance for Whitehead in subsequent years (somewhat surprisingly, given its prevalence in the lectures). Of special importance to Whitehead was the work of his new Harvard colleague Lawrence Henderson, whose book The Fitness of the Environment he recommended to his students’ attention.