Download the lastest shadow source which seems to be http://www.nanotech.wisc.edu/shadow/source/shadow-20020811.tar.gz or, perhaps http://ftp.esrf.eu/pub/scisoft/shadow/source/shadow-20020811.tar.gz "tar zxvf" and cd to the shadow-20020811 directory. There will be two corrections necessary. Tokenization seems to have changed in the C-preprocessor: ./src/utils/cnamelist/namelist.c line 89 ./src/utils/special/chval/chval.c line 72 Both have the same error: Change # define G_ARRAY_ELEM(a,i) a ## ( ## i ## ) to # define G_ARRAY_ELEM(a,i) a(i) Shadow requires g77... neither gfortran nor ifort will work. (Can we fix this?) Now you may do the ./configure --prefix=/path/to/shadow-20020811 and make install The final piece is to cd ../shadow-2.3.0-linux and edit .shadowrc.sh such that SHADOW_ROOT now points to the shadow-20020811 directory and all should be set. ====================================================================================== These instructions worked for a Fedora Core 6 machine (2.6.22.14-72) and my Scientific Linux 5.0 box (2.6.18-92.1.10.el5). David Gore dgore_at_bio.aps.anl.gov