α,β-Unsaturated alkenyl or propargyl alcohols add propargyl,allyl and benzyl Grignard Reagent at the β-position of the alcohol, yielding methylene or methyl substituted alcohols in moderate yield. Alkenes and alkynes with no alcohol functionality or alcohols with no α, β-unsaturated functionality failed to react. Saturated Grignards gave very low yields. The mechanism is postulated to involve a cyclic transition state with an initial complex of the hydroxyl on the alcohol to the magnesium of the Grignard. The reaction has synthetic utility for the production of 2-methylene substituted alcohols