This research examines the performance of agricultural land protection and growth management tools (primarily zoning regulations) used by Story County, Iowa, in implementing the policies of its County Development Plan (CDP). Farmland conversion and zoning permit activity from 1983 - 1998 were mapped and evaluated. Zoning permit activity was evaluated for its "compactness" and location within identified growth areas as designated on the CDP. The agricultural quality of converted land as measured by an average Corn Suitability Rating (CSR) was calculated. These results were then evaluated against the county policies for protecting high value agricultural lands, promoting compact development patterns and directing new development toward identified growth areas. Geographic Information System (GIS) software was used to perform much of the analysis and to display the spatial distribution of farmland conversion and zoning permit activity.;The GIS software was also used to evaluate the quality of agricultural land lost to development. The research shows for the study period (1983 - 1998) that 70 percent of new development was located within two miles of cities, compared to 86 percent of new development approved under the "growth management" provisions of the zoning regulations since adoption of the CDP. The research also shows that the percentage of permits within one mile of cities has increased since the adoption of the CDP, indicating a trend toward greater "compactness, " The county has defined "prime" agricultural soils as those with a CSR of 62 or above. The research shows the average CSR of all parcels issued residential permits is 62, while those parcels issued permits under the "low value for agriculture" provision had an average CSR of only 58.;Based on the research, it is concluded that certain provisions of the zoning ordinance are weak in terms of achieving the stated goals of the CDP and of the generally accepted principles of growth management. However, other zoning provisions are fairly effective in achieving both the CDP goals and the principles of growth management.