Like many domains of professional psychology, school psychology continues to struggle with the problem of distinguishing scientific from pseudoscientific and otherwise questionable clinical practices. We review evidence for the scientist-practitioner gap in school psychology and provide a user-friendly primer on science and scientific thinking for school psychologists. Specifically, we (a) outline basic principles of scientific thinking, (b) delineate widespread cognitive errors that can contribute to belief in pseudoscientific practices within school psychology and allied professions, (c) provide a list of 10 key warning signs of pseudoscience, illustrated by contemporary examples from school psychology and allied disciplines, and (d) offer 10 user-friendly prescriptions designed to encourage scientific thinking among school psychology practitioners and researchers. We argue that scientific thinking, although fallible, is ultimately school psychologists' best safeguard against a host of errors in thinking. (Contains 3 tables.)