Stratigraphic investigations, pollen analysis and ₁₄C dating were used to investigate the history of the Neolithic-Bronze Age occupation site at Ballynagilly and to relate this to the pre-historic occupations. A series of ₁₄C measurements from the mire were used to establish a deposition rate curve from which a time scale for the vegetation history was derived. This was also used to correlate the vegetation history with ₁₄C dated prehistoric occupations. Organic accumulation began in the deep mire about 8000 B. C. and the earliest blanket peats began forming around 1000 B.C. In the early Littletonian Stage (Postglacial), a juniper phase gave way to birch and willow at 7450 B.C. Until 6050 B.C., there was a period of low water level with a rich mire vegetation. Elm, oak, hazel, and pine entered simultaneously at 6050 B.C. creating a dense forest cover. Alder first appeared at 4970 B.C. but did not expand until 3500 B.C. The mid-Postglacial was examined in detail and showed evidence of Neolithic forest clearance involving burning. Charcoal of pine, oak, and hazel, ₁₄C dated to approximately 3200 B.C. was discovered. This date coincides with those for a Neolithic house and other associated features. The Neolithic clearance phase lasted some hundreds of years with periods of minor forest regeneration. During this phase, different types of agriculture may have been used. A total recovery of the forest, albeit with a different composition, was deduced to have taken place before new clearance in Beaker times at around 200 B.C. Somewhat before this, at 2200 B.C., the final decline of pine pollen occurred but was apparently unconnected with human activity. Heath began to develop at 1800 B.C. and increased in extent following Early Bronze Age clearance of scrub woodland at 1650 B.C. Various clearance episodes from this time through to 200 B.C. caused a further progressive deforestation. Brief regeneration after 200 B.C. was followed by indications of locally wetter conditions and renewed deforestation at 450 A.D. Despite some scrub regeneration around 800 A.D. continuing pressures on the woodland culminated in an open landscape by 1500 A.D. -- AATA