THE MODEL PENAL CODE (MPC) REQUIRES A THRESHOLD INQUIRY CONCERNING WHETHER THE HARM THAT OCCURRED WOULD HAVE COME ABOUT IN THE ABSENCE OF THE DEFENDANT'S CONDUCT. IF IT WOULD NOT, THEN CAUSATION IN FACT IS ESTABLISHED. THE ADEQUACY OF THE 'BUT-FOR' STANDARD IS EXAMINED IN LIGHT OF THE POLICIES UNDERLYING THE DIFFERENTIATION OF PUNISHMENT BASED ON THE OCCURRENCE OF HARM. THE PURPOSES SERVED BY SUCH DIFFERENTIATION ARE DISCUSSED IN CONJUNCTION WITH THE LIMITATIONS OF THE MPC STANDARD. ALTERNATIVE FORMULATIONS ARE CONSIDERED, INCLUDING THE STANDARD OF SUBSTANTIAL CONTRIBUTION WHICH WOULD ALLOW A JURY TO DECIDE WHETHER THE DEFENDANT'S ACTIONS WERE SUFFICIENTLY SIGNIFICANT TO JUSTIFY HIS ACCOUNTABILITY. CAUSATION IN FACT DOES NOT, HOWEVER, ESTABLISH LIABILITY. FURTHER INQUIRY IS REQUIRED INTO THE QUESTION OF PROXIMITY TO PREVENT A DEFENDANT FROM BEING HELD RESPONSIBLE WHEN THE RESULT OF HIS CONDUCT DIFFERS GREATLY FROM THAT ANTICIPATED OR RISKED. ARGUMENT IS OFFERED IN SUPPORT OF THE PROXIMITY STANDARDS OF THE MPC, (WHICH INCORPORATE THE DOCTRINE OF TRANSFERRED INTENT) BUT GREATER FLEXIBILITY IS RECOMMENDED. ALTHOUGH A SEPARATE PROVISION OF THE MPC GOVERNS ACCOMPLICE LIABILITY, NO SHARP LINE DIVIDES THE ISSUES, AND VICARIOUS LIABILITY MAY BE INDIFFERENTLY PREDICATED ON OTHER PROVISIONS. WITHIN SPECIFIED LIMITATIONS, STANDARDS OF PERSONAL RESPONSIBILITY REPRESENT A SIGNIFICANT INDEPENDENT BASIS OF LIABILITY FOR HARM CAUSED BY ANOTHER'S CONDUCT. A REDRAFTING OF THE CAUSATION AND PROXIMITY PROVISION IS OFFERED. FOOTNOTES ARE PROVIDED. (TWK)