Heather Wolfe isn’t a Shakespeare expert, but she can do something many Shakespeare scholars can’t: She can read his handwriting.

In 16th- and 17th-century England, most documents were written in a style of cursive writing called secretary hand. To the untrained eye, it is nearly impenetrable. The “h” looks like a butcher’s hook; “m,” “n,” “i” and “u” often are indistinguishable. An “s” might look like a numeral 6—or a carrot.

Dr. Wolfe, curator of manuscripts and archivist at the Folger Shakespeare Library in Washington, D.C., specializes in reading these documents. Now she is leading a project to digitize, transcribe and post online every known reference to Shakespeare and his family written in and around his lifetime. She is discovering details that have been overlooked for centuries, from mistranscriptions and mysterious seals to an unpublished document tucked away in the Venice state archives that describes Italian and French diplomats attending “Pericles” in London.

No handwritten drafts of Shakespeare’s plays survive—only published editions. But there do exist three pages that scholars believe Shakespeare wrote by hand to revise a play called “Sir Thomas More” by Anthony Munday and Henry Chettle. Those pages are in secretary hand.

Dr. Wolfe’s project began when she was conducting research for an exhibition of 50 Shakespeare-related documents currently on view at the Folger through March 27, for the 400th anniversary of the playwright’s death. To prepare for the exhibition, she traveled to museums and libraries across the U.K., examining and transcribing documents before they arrived at the Folger on loan.