Nanocrystalline diamond films thinner than 140 nm are demonstrated to exhibit Young's moduli as high as single crystal and microcrystalline bulk diamond when grown under appropriate conditions. The Young's modulus of nanocrystalline diamond is shown to be a function of the methane concentration and the microwave power density when grown by microwave plasma enhanced chemical vapour deposition. The variation of Young's modulus can be correlated with the sp(2) content and crystallite size of the films as characterised by Raman spectroscopy and Scanning Electron Microscopy. (C) 2010 Elsevier B.V. All rights reserved.