We introduce an authorship identification test, called modal analysis, based on a new statistic derived from the Karhunen-Loeve transform. Application to the poems of the Shakespearean canon and to other contemporary poetry strongly supports the case for disqualification of most major claimants. Results also cast doubt that the recently discovered poems, Shall I Die and Elegy, were written by William Shakespeare, but do suggest that eight unascribed poems of The Passionate Pilgrim may have been his work.