The Christian Science Board of Directors is a five-person executive entity created by Mary Baker Eddy to administer the Christian Science Church under the terms defined in her equivalent of a church constitution, the Church Manual. Its functions and restrictions are defined by various By-Laws throughout the Manual.

The Board (occasionally TCSBD or the BoD for short) also includes functions defined by a Deed of Trust written by Eddy (one of several, in fact) under which it consisted of four persons, though she later expanded the Board to five persons, thus in effect leaving one of its members out of Deed functions. This later bore on a dispute during the 1920s, known as the Great Litigation in CS circles, pivoting on whether the CSBD could remove trustees of the Christian Science Publishing Society or whether the CSPS trustees were established independently.

While Eddy's Manual established limited executive functions under the rule of law in place of a traditional hierarchy, the controversial 1991 publication of a book by Bliss Knapp led the then Board of Directors to make the unusual affadavit during a suit over Knapp's estate that neither acts by it violating the Manual, nor acts refraining from required action, constituted violation of the Manual. A traditionally-minded minority held that the Board's act in publishing Knapp's book constituted a fundamental violation of several by-laws and its legal trust, automatically mandating the offending Board's resignations under Article I, Section 9.

Another minority believed that Eddy intended various requirements for her consent (in their view, "estoppels") to effect the church's dissolution on her passing, since they could no longer be followed literally. Ironically, one of the stronger arguments against this position came from an individual highly respected by their theological quarter, Bliss Knapp, who claimed that Eddy understood through her lawyer that these consent clauses would not hinder normal operation after her decease.