Photoresist compositions that demonstrate superior photolithographic performance and hardened resist films that show superior resistance to solvents, have excellent resistance to under plating during the electrodeposition of metals, and show excellent resist stripping characteristics. These photoresist compositions according to the invention are well-suited as for applications in the manufacture of MEMS and micromachine devices. These photoresist compositions according to the invention comprise one or more epoxide-substituted, polycarboxylic acid Resin Component (A), one or more photoacid generator compounds (B), and one or more solvent (C).