The grade of W can be assigned to a course only after the last day to drop or withdraw without receiving a grade (generally four weeks into the semester) through the last day to drop or withdraw (generally four weeks prior to the last day of classes in a fall or spring semester). Students are responsible for initiating action to withdraw from a class. 

Beginning Fall 2007, undergraduates are limited to 6 Ws in their academic career.

Information is available on the Provost website at http://www.uh.edu/provost/stu/6-Ws_faq_stu.html.