The number of land trusts in a state varies widely across the United States. Could such variation make economic sense? This paper models the optimal number of private conservation agents in a region and highlights two competing forces: spatial externalities in conservation that increase the efficiency of having few agents and diversity in conservation goals that means that specialization and de-concentration can be efficient. A state-level, count data analysis indicates that some observed patterns in the numbers of trusts are consistent with patterns expected in the optimal numbers of trusts. Some results identify areas for research and possible policy intervention.