Process models have been suggested as a basis for forest monitoring. A process model-based system yields biologically interpretable data according to a particular hypothesis of forest biology. But there is a potential tradeoff between the need for practicality in an operational monitoring system and the need for realism in the underlying model(s). Despite their realism, process models are sometimes viewed as impractical for monitoring because they incorporate too much detail, require too many measurements, or need better calibration. However, process models can be applied to forest health monitoring in at least three ways. An analogy with human health monitoring motivates the use of forest process models in designing a forest health monitoring system.