This issue provides information about theories and practices associated with Problem-based learning (PBL). Partially because of changes in the Information Age that are transforming the nature of knowledge and the types of problems that people face, professors are adopting PBL in order to facilitate a broader and more up-to-date role of what it means "to learn." Professors will encounter, however, their own set of problems when designing and implementing a problem-based curriculum. Not unlike PBL assignments to their students, the issues and obstacles professors will encounter require practical solutions. The authors of this issue have practical experience in the design and implementation of PBL. Based on their experiences, they offer insightful commentaries and useful guidelines about various aspects of PBL. These guidelines include ideas for designing useful problems that can serve as the basis of PBL activities, creating environments conducive to problem solving, facilitating students' problem solving activities, and assessing students' efforts in problem solving. This is the 95th issue of the quarterly journal "New Directions for Teaching and Learning".