Pressure sensitive adhesive compositions are described comprising at least one low Tg ethylenically unsaturated monomer, and at least one silsesquioxane polymer crosslinker comprising a plurality of ethylenically unsaturated groups. The low Tg ethylenically unsaturated monomer typically has a Tg no greater than 10° C. In some embodiments, the composition comprises at least 50, 55, 60, 65, or 70 wt-% of low Tg ethylenically unsaturated monomer. The low Tg ethylenically unsaturated monomer is typically an alkyl (meth)acrylate comprising 4 to 20 carbon atoms. In another embodiment, an adhesive composition is described comprising a syrup. The syrup comprising i) a free-radically polymerizable solvent monomer; ii) a solute (meth)acrylic polymer comprising polymerized units derived from one or more alkyl (meth)acrylate monomers, and iii) at least one silsesquioxane polymer crosslinker comprising a plurality of ethylenically unsaturated groups. The free-radically polymerizable solvent monomer, polymerized units of the solute (meth)acrylic polymer, or a combination thereof comprise a low Tg ethylenically unsaturated monomer. Also described are pressure sensitive adhesive articles and method of preparing adhesive articles.