THE FIRST STEP IN THE STANDARD MODEL FOR PLANET FORMATION IS THE GROWTH OF GRAVITATIONALLY BOUND BODIES CALLED ``PLANETESIMALS'' FROM DUST GRAINS IN A PROTOPLANETARY DISK. CURRENTLY WE DO NOT KNOW HOW PLANETESIMALS FORM HOW LONG THEY TAKE TO FORM OR WHAT THEIR SIZES AND MECHANICAL PROPERTIES ARE. THE GOAL OF THIS PROPOSAL IS TO ASSESS HOW THESE UNCERTAINTIES AFFECT SUBSEQUENT STAGES OF PLANETARYGROWTH AND THE KIND OF PLANETARY SYSTEMS THAT FORM. THE WORK WILL ADDRESS THREE PARTICULAR QUESTIONS: (I) CAN THE PROPERTIES OF SMALL BODY POPULATIONS IN THE MODERN SOLAR SYSTEM CONSTRAIN THE PROPERTIES OF PLANETESIMALS? (II) HOW DO THE PROPERTIES OF PLANETESIMALS AFFECT THE FORMATION OF GIANT PLANETS? (III) HOW DOES THE PRESENCE OF A WATER ICE CONDENSATION FRONT (THE ``SNOW LINE'') IN A DISK AFFECTPLANETESIMAL FORMATION AND THE LATER STAGES OF PLANETARY GROWTH?THESE QUESTIONS WILL BE EXAMINED WITH COMPUTER SIMULATIONS OF PLANET FORMATION USING NEW COMPUTER CODES TO BE DEVELOPED AS PART OF THE PROPOSAL. THE FIRST QUESTION WILL BE ADDRESSED USING A STATISTICAL MODEL FOR PLANETESIMAL COAGULATION AND FRAGMENTATION. THIS CODE WILL BE MERGED WITH THE PROPOSER'S MERCURY N-BODY INTEGRATOR CODE TO MODEL THE DYNAMICS OF LARGE PROTOPLANETS IN ORDER TO ADDRESSTHE SECOND QUESTION. FINALLY A SELF-CONSISTENT MODEL OF DISK EVOLUTION AND THE RADIAL TRANSPORT OF WATER ICE AND VAPOUR WILL BE ADDED TO EXAMINE THE THIRD QUESTION.A THEORETICAL UNDERSTANDING OF HOW PLANETS FORM IS ONE OF THE KEY GOALS OF NASA AND THE ORIGINS OF SOLAR SYSTEMS PROGRAMME.RESEARCHERS HAVE CARRIED OUT MANY STUDIES DESIGNED TO ADDRESS THIS GOAL BUT THE QUESTIONS OF HOW PLANETESIMALS FORM AND HOW THEIR PROPERTIES AFFECT PLANET FORMATION HAVE RECEIVED RELATIVELY LITTLE ATTENTION. THE PROPOSED WORK WILL HELP ADDRESS THESE UNSOLVED QUESTIONS AND PLACE OTHER RESEARCH IN CONTEXT BY ASSESSING THE IMPORTANCE OF PLANETESIMAL ORIGINS AND PROPERTIES FOR PLANET FORMATION.