WITH IMPACTS ON SPACE-BASED AND GROUND-BASED ASSETS SPACE WEATHER HAS BECOME A NECESSARY NATIONAL PRIORITY. AS ONE ASPECT OF SPACE WEATHER SOLAR ENERGETIC PARTICLE (SEP) EVENTS ARE A SIGNIFICANT HAZARD DIRECTLY TO ASTRONAUTS (THROUGH INCREASED RADIATION LEVELS) AND SATELLITES (CAUSING E.G. SINGLE-EVENT UPSETS GHOST COMMANDS SOLAR CELL DAMAGE) AS WELL AS INDIRECTLY THROUGH IONIZATION OF THE IONOSPHERE INTERFERING WITH RADIO COMMUNICATIONS. WHILE THE BASIC PROCESS OF ACCELERATING SEPS AT SHOCKS DRIVEN BY CORONAL MASS EJECTIONS (CMES) IS FAIRLY WELL UNDERSTOOD THE DETAILS THAT LEAD TO THE SUBSTANTIAL VARIATION IN SEP COMPOSITION OBSERVED AT 1 AU REMAIN ELUSIVE. THIS IS PARTICULARLY UNDERSCORED BY THE OBSERVATION OF LARGE FE-RICH SEP EVENTS WHICH SEVERELY CALLED INTO QUESTION THE EXISTING SIMPLE TWO-CLASS PARADIGM OF SEP EVENTS (THOUGHT TO REPRESENT TWO DISTINCT ACCELERATION MECHANISMS). TO DATE COMPETING HYPOTHESES FOR THE GENERATION OF THESE EVENTS HAVE NOT BEEN SUFFICIENTLY TESTED TO ACHIEVE RESOLUTION AND FURTHER OUR UNDERSTANDING OF PARTICLE ACCELERATION NEAR THE SUN. WE PROPOSE A TWO-PRONGED APPROACH TO ADVANCE OUR KNOWLEDGE OF SEP COMPOSITIONAL VARIATIONS. WE WILL USE SOPHISTICATED MODELING OF THE CME AND MAGNETIC FIELD ENVIRONMENT NEAR THE SUN AND DETAILED SEP AND SOLAR EVENT STUDIES UTILIZING THE STATE OF THE ART INSTRUMENTATION ON ACE STEREO SDO AND SOHO TO ANSWER OUR CENTRAL QUESTION: HOW IS THE COMPOSITIONAL VARIABILITY OF SEP EVENTS INFLUENCED BY THE MAGNETIC ENVIRONMENT IN WHICH THEY OCCUR? AND THE SECONDARY QUESTION: WHAT IS THE ROLE OF PRE-EVENT SOLAR ACTIVITY? A STRONG IMPEDIMENT TO PROGRESS ON THESE QUESTIONS HAS BEEN THE LACK OF INFORMATION ON THE CONDITIONS OF THE SHOCK WAVE CONNECTED TO THE OBSERVER THROUGHOUT THE SEP EVENT INCLUDING THE ANGLE BETWEEN THE SHOCK SURFACE NORMAL AND THE MAGNETIC FIELD AND THE SHOCK COMPRESSION RATIO AND ALFVEN MACH NUMBER. THESE QUANTITIES ARE HARD TO DETERMINE OR ESTIMATE FROM REMOTE-SENSING OBSERVATIONS ALONE. WE WILL USE THE 3D MHD MODEL SWMF/AWSOM WHICH CAN REPRODUCE MOST OF THE OBSERVED FEATURES IN THE CORONA QUANTITATIVELY WITH UNPRECEDENTED FIDELITY TO ACCESSIN-SITU MEASUREMENTS OF THE CME-DRIVEN SHOCK WAVES FROM THE CORONA OUTWARD. THESE WILL THEN BE STUDIED IN CONNECTION WITH DETAILED SEP COMPOSITIONAL ANALYSIS AT A LEVEL THAT HAS NOT BEEN PERFORMED FOR THE VAST MAJORITY OF CYCLE 24 EVENTS (AND SOME CYCLE 23 EVENTS). THE SOLAR STUDIES WE PROPOSE WILL BE USED TO RELATE THE PRECEDING SOLAR STRUCTURE AND ACTIVITY AS WELL AS DETAILED EVENT ERUPTION ANALYSIS TO BOTH THE EVOLUTION OF THE MAGNETIC FIELD AS CALCULATED BY AWSOM AND THE RESULTING SEP CHARACTERISTICS. FINALLY THE ROLE OF SUPRATHERMALS WILL BE INVESTIGATED THROUGH SYSTEMATIC COMPARISONS OF THE COMPOSITION OF UPSTREAM SUPRATHERMAL PARTICLES TO THAT OF SEP EVENTS THE CONNECTION BETWEEN CERTAIN TYPES OF SOLAR ACTIVITY (E.G. CORONAL JETS) TO OBSERVED 3HE-RICH SEP EVENTS AND A SURVEY OF THE FULL COMPOSITIONAL VARIABILITY OF 3HERICH SEP EVENTS IN CYCLE 24 (WHICH HAS NOT BEEN DONE) AND SUBSEQUENT DIFFERENCES BETWEEN CYCLE 23 AND 24. OUR PROPOSED WORK WILL YIELD SIGNIFICANT ADVANCES IN UNDERSTANDING THE COMPOSITIONAL VARIABILITY SEP EVENTS. ADDITIONALLY IT WILL YIELD VALUABLE INFORMATION REGARDING THE EVOLUTION OF CMES AS THEY PROPAGATE OUTWARD FROM THE SUN AND THEIR DRIVEN SHOCKS AND THE CHARACTERISTICS OF SEVERAL TYPES OF SOLAR ACTIVITY (E.G. JETS AND EUV WAVES). THUS OUR STUDIES ADDRESS TWO OF THE KEY DECADAL SURVEY SCIENCE GOALS: 1)DETERMINE THE ORIGINS OF THE SUN'S ACTIVITY AND PREDICT THE VARIATIONS IN THE SPACE ENVIRONMENT AND 4) DISCOVER AND CHARACTERIZE FUNDAMENTAL PROCESSES THAT OCCUR BOTH WITHIN THE HELIOSPHERE AND THROUGHOUT THE UNIVERSE. FINALLY THE RESULTS OF OUR WORK WILL BE CRITICAL FOR NOT ONLY THE SCIENCE OF PARTICLE ACCELERATION BUT ALSO FOR FUTURE SPACE WEATHER PREDICTION THROUGHOUT THE HELIOSPHERE.