Tracking is a necessity for interactive virtual environments. Marker-based tracking solutions involve the placement of fiducials in a rigid configuration on the object(s) to be tracked, called a tracking probe. The realization that tracking performance is linked to probe performance necessitates investigation into the design of tracking probes for proponents of marker-based tracking. A challenge involved with probe design is predicting the accuracy of a tracking probe. We present a method for predicting the accuracy of a tracking probe based upon a first-order propagation of the errors associated with the markers on the probe. Results for two sample tracking probes show excellent agreement between measured and predicted errors.