An aqueous emulsion polymer suitable for use in thickening aqueous compositions including, as copolymerized units: from 8% to 25 wt %, based on polymer weight, acid-containing monomer, from 2% to 30 wt %, based on polymer weight, (meth)acrylic acid ester of the formula: H.sub.2C.dbd.C(R)--C(O)--O--(CH.sub.2--CH.sub.2O).sub.n--R.sub.o, wherein R is H or CH.sub.3, n is from 2 to 100 and R.sup.o is a group containing from 4 to 36 carbon atoms, and from 35% to 90 wt %, based on polymer weight, (C.sub.1-C.sub.4) alkyl (meth)acrylate; wherein the polymer is formed by a living free radical polymerization process, alternatively in the presence of a compound containing the group --C(.dbd.S)--S--, is provided. An aqueous composition including the aqueous emulsion polymer and a polymeric coating including the polymer are also provided as are certain related processes.