Though complexity and temporal change in the organization of agricultural production systems have been demonstrated at regional and national level, little evidence has been published on these topics at the individual farm scale. The object of this paper is to demonstrate the degree of complexity and change of farming system on a sample of holdings from central Somerset over a known period. Results indicate that though dairy production predominates in the region, many farms operate a range of subsidiary or alternative enterprises, and the emphasis, both in dairy production and other enterprises, has changed considerably over the period in question. IT is recognized in agricultural geography that in order to understand patterns of agricultural production, emphasis must be placed upon the way in which crop and livestock enterprises are combined, to produce distinctive systems of production, within particular regions. A number of authors' have demonstrated these interrelationships in various parts of the world, but much of this work has been of a generalized nature, depending upon published data for administrative areas of various sizes. Though it is recognized that such regional patterns as emerge from these studies are merely a cumulative expression of the production systems of farms within them, and that 'ideally, all studies relating to the geography of agriculture, ought to be based on information for individual farms',2 few examples are to be found of such studies being carried out at the individual farm level.3 In addition it is realized that in order to remain profitable, farm systems must respond dynamically to temporal changes in factors of production,4 which leads to changes through time in the importance of particular crop or livestock enterprises within farm production systems. Again, such changes have been illustrated at the national5 and regional6 levels, but few studies have been published on the nature of such changes at the farm level.7 The major objectives of this study, therefore, are to investigate the enterprise components of the production systems of individual farms within a small survey area, to illustrate their degree of complexity, and to demonstrate the type and degree of change in systems organization which has taken place on these farms, over a measured time period. SURVEY AREA AND DATA SOURCES The chosen study area consists of some 400 km2 of central Somerset, south of Glastonbury (Fig. (Fig. I), a region of sharp physical contrasts, isolated hills being flanked in the east by low clay vales, and surrounded in the west by low-lying, ill-drained 'levels'.8 Though physical contrasts offer a range of land quality,9 farming has been mainly orientated towards dairying, from at least the beginning of the eighteenth century,' and the area forms a core region within a larger south-west dairying district.I A number of studies confirm the dominance of milk production on a high proportion of farms'2 and suggest few viable alternatives to dairying.13 A simplistic judgement based on this evidence might suggest that within such a region,