MCGR is a Monte-Carlo program for determining the pair correlation function (pcf), G(r), of a material from the total structure factor (tsf), F(Q), by an inverse method. Some of the latest developments are reviewed here: (a) coordination constraints, (b) Gaussian smoothing, (c) refinement of a quadratic background and (d) pcf's for crystalline powders. Experience suggests that MCGR can be used as a sensitive test of data quality, allowing the rapid assessment of instrument performance.