Description: This work is essentially an update of previous compilations of information on the diffusivity of elements in semiconductor-grade silicon. It subsumes the data contained in B.L.Sharma’s monograph on ‘Diffusion in Semiconductors‘ (Trans Tech Publications, 1970), plus the data contained in Diffusion and Defect Data (Diffusion in Silicon) Volume 45 (1986), Defect and Diffusion Forum (Diffusion in Silicon - 10 years of Research) Volumes 153-155 (1998), Defect and Diffusion Forum (Diffusion in Silicon - a Seven-Year Retrospective) Volume 241 (2005) and the latest data from recent Semiconductor Retrospectives: Defect and Diffusion Forum, Volumes 245-246, Volumes 261-262, Volume 272 and Volume 282. In addition, the resultant 400 items of data were analysed in the hope of finding some unifying correlation. It was indeed found that all of the points (each the average of many independent measurements) seemed to fall on a number of distinct straight lines passing through the origin of a plot of activation energy versus atomic radius. However, it remained unclear how these correlations could be explained.