You can explicitly specify which version of a package you want to install. For example, if you wanted to install an older version of Tornado, pip install torn

You can explicitly specify which version of a package you want to install. For example, if you wanted to install an older version of Tornado, pip install tornado==1.1 OR if you know you ONLY want tornado 2.0 pip install tornado==2.0 From my experience, pip has been able to fetch PYTHON dependencies if the author of the package wrote their setup.py correctly. I agree that things could be better with regards to C dependencies (MySQL-Python requiring libmysql5dev being particularly annoying) but this is hard to do as every environment has their own way of naming dependent libs.