We transformed an upper-division electricity and magnetism course for physics and engineering majors using principles of active engagement and learning theory. The teaching practices and new curricular materials were guided by observations and interviews to identify common student difficulties.  We established explicit learning goals for the course, created homework that addressed key aspects of those learning goals, offered interactive help room sessions, created and ran small-group tutorial sessions, and used interactive classroom techniques such as peer discussion and "clickers."  We find that students in the transformed course exhibit improved performance over the traditional course, as assessed by common exam questions and a newly developed conceptual post-test. These results suggest that it is valuable to further investigate how physics is taught at the upper-division, and how PER may be applied in this context.