A collection of approximately 5,000 compounds rationally selected according to various diversity parameters and Astex Rule of Three considerations (MW ≤ 300, H-bond donors ≤ 3, H-bond acceptors ≤ 3, cLogP ≤ 3). The fragment library contains fragments with both free and protected functionality. Structural diversity of the Fragment Library has been independently assessed, confirming that the overall selection displays good diversity.