Given the increasing importance of soft skills in the computing profession, there is good reason to provide students withmore opportunities to learn and practice those skills in undergraduate computing courses. Toward that end, we have developed an active learning approach for computing education called the "Pedagogical Code Review" (PCR). Inspired by the "code inspection" process used in the software industry, a PCR is a collaborative activity in which a small team of students, led by a trained moderator: (a) walk through segments of each other's programming solutions, (b) check the code against a list of best coding practices, and (c) discuss and log issues that arise. To evaluate the viability and effectiveness of this approach, we conducted a series of four mixed-method empirical studies of various implementations of PCRs in CS1 courses at Washington State University. The first study validated the viability of the PCR activity. Using a quasi-experimental design, the final three studies evaluated two alternative implementations of PCRs--"face-to-face" and "online." Our results provide evidence that PCRs can promote positive attitudinal shifts, and hone skills in critical review, teamwork, and communication. Based on our findings, we present a set of best practices for implementing PCRs.