The Fryske Akademy is planning to produce a Syntax of Old West Frisian, as part of a larger project on Old West Frisian grammar, law and culture. A number of requirements are presented which a syntax of Old Frisian must ideally meet (cf. Mitchell 1985, (Ringe &) Taylor 2014 on Old English, Van der Horst 2008 on Old and Middle Dutch, Bor 1971, De Haan 2001 and Bremmer 2009 on Old Frisian). Then I go on to present a case study about negation in Old Frisian, arguing that each of the three phases of Jespersen’s cycle is attested in Old Frisian. We can nicely trace Jespersen’s Cycle in OF, because we often have the same text in versions from different centuries. In other cases, the Cycle helps us in establishing the relative chronology of undated manuscripts. To conclude, I point out some fascinating mysteries in the field of OF studies