This seminar begins by discussing basic concepts of boundary law including: Senior and Junior Rights; Sequential and Simultaneous Conveyances; Excess, Deficiency, and Proration; Order of Importance of Conflicting Elements; Control of Monuments; Control Between Conflicting Monuments; Adverse Possession; and Acquiescence and Estoppel. Good measurement skills and a solid understanding of boundary law concepts are important for surveyors; but often overlooked is the need for common sense. We will explore the need and the path to achieving it. The seminar will conclude with a discussion of the functions and duties of the surveyor, with regard to the client, the public, and the profession. The discussion will examine when a surveyor should or should not express a professional opinion, and the often-thorny issue of possession lines versus measured “deed lines”.