The invention provides a resist composition which comprises a polymer (a) having structural units with an acid-labile group, and a radiation-sensitive compound (b) which forms an acid upon exposure to activated radiation, wherein the polymer (a) is a polymer obtained by polymerizing 10 to 100 wt. % of a (meth)acrylic ester (i) having, as an alcohol residue, an allyl group with at least two substituent groups and 0 to 90 wt. % of a monomer (ii) copolymerizable with the (meth)acrylic ester, and has excellent sensitivity, resolution and heat resistance, and a pattern forming process making use of the resist composition.