I installed pipenv by following the instructions here. From the Windows command prompt I ran pip install --user pipenv which returned the message Successfully installed pipenv-5.3.3 Now I want to install the requests package using pipenv, so I ran pipenv install requests but this returned 'pipenv' is not recognized as an internal or external command, operable program or batch file. I have added the path C:\Users\Robert\AppData\Roaming\Python\Python35\site-packages to my Windows path environment variable, but I still receive the same error. How can I install the requests package using pipenv? EDIT: As I have remnants of Python 3.5 and Python 3.6 on my system, I'm going to uninstall everything and start anew. (I've just started learning Python and I want to keep this as simple as possible.) Continue reading...