PYTHIA7 is built on top of the Toolkit for High Energy Physics Event Generation - ThePEG which has been broken out from PYTHIA7 to better factorize the parts which were PYTHIA-specific from those which are general model-independent components of the toolkit and which can be used by any event generator model.
The current versions of Pythia7 and ThePEG is 1.6.1 and are available as a compressed tar file: ThePEG++-1.6.1.tar.gz. For installation instructions, please consult the joint ThePEG/Herwig++ wiki pages.
There is no up-to-date documentation available for Pythia7 and ThePEG,
but the basic structure is very similar to the earlier versions of PYTHIA7
program which is described in Comput. Phys. Commun. 134 (2001) 365
(available in HTML and postscript
format. Proper documentation is under construction using the
Doxygen documentation system. The current state of this is available
If you need more information, or if you have found problems or bugs in the current version, please send me an email.