You usually don't need to add the location of Qt library to the system variable. Qt Creator can automatically scan the Qt library versions existing in the system. If you can't scan, you can use the tool-> Options-> Add the path to the static library in Qt4. Although QDevelop is not that smart, it can manually specify the locations of INCLUDE and LIB. Maybe it's not a problem at all. If you miss the dynamic library, or don't want to experience the snail-like speed of static compilation before product release, you can specify CONFIG += shared in the pro file, and remember to choose the corresponding version in Project.