Purpose: The National Association for Professional Development Schools (NAPDS) recognizes that there is a tendency for the term "PDS" (Professional Development School) to be used as a catch-all for various relationships that constitute school--university partnership work. The intent of this NAPDS statement is to assert the essentials, or fundamental qualities, of a PDS. NAPDS encourages all those working in school--university relationships to embrace the Nine Essentials of PDSs communicated in this statement. The Essentials are written in tangible, rather than abstract, language and represent practical goals toward which work in a PDS should be directed. Design/Methodology/Approach: Policy statement. Findings: NAPDS maintains that these Nine Essentials need to be present for a school-university relationship to be called a PDS. Without having all nine, the relationship that exists between a school/district and college/university, albeit however strong, would not be a PDS. How individual PDSs meet these essentials will vary from location to location, but they all need to be in place to justify the use of the term "PDS." Practical Implications: For those in established PDSs, some aspects of this document will be confirmed, while other aspects may be identified as needing attention. For those aspiring to establish PDSs, the authors offer this statement as a useful guide for their work. NAPDS invites individuals involved in school--university partnerships to share this statement with colleagues in the spirit of continuous improvement. By coming to terms with the challenges and opportunities inherent in this statement, the study can collectively fulfill the vision of this remarkable and distinct partnership called PDS. Originality/Value: This policy statement articulates how the Nine Essentials are the foundation of PDS work.