The 46th Arden Conference, held in West Point, NY, USA, March 2011, focused on development of protein therapeutics, comprising preformulation, formulation, manufacturing, advanced delivery systems, protein characterization/analysis, and regulatory landscape. The sessions of preformulation and formulation development consisted of nine lectures discussing protein stability implications and characterization during purification, freeze-drying and manufacturing. The session on advanced drug delivery encompassed two new sustained-release microsphere formulations (protein microencapsulation by annealing of premade porous PLGA microspheres and aqueous-aqueous emulsion for preformulating proteins to solvent-resistant particles), two transdermal insulins (patching after thermal ablation of skin and phase-transition hydrogel microneedle patch), and a responsible hydrogel system for intra-ear delivery. The sessions on analytical technologies and regulatory landscape both focused on challenges for biosimilars.