Plant communities in the southern Coast Range of California form a mosaic with discrete to gradual transitions between multiple vegetation types. To accurately portray this pattern and to quantify the areal coverage of ecotonal space, a new method of mapping vegetation was developed. Vegetation stands were classified and mapped in separate GIS layers to the full extent of their respective suite of indicator species. Since all stands were mapped in this way, the overlap of different communities in the GIS represents ecotonal space. Vegetation mapping was entirely ground-based using a GPS receiver. Vegetation classification followed the Holland and Keil scheme. Eleven plant communities were identified within the 92.6 ha study area. This mapping method revealed that 32% of the total area was ecotonal and that the majority of plant communities exhibited a greater portion of their total area as ecotone than as discrete space. This finding suggests that typical vegetation maps depicting discrete boundaries between all vegetation types may misrepresent a nontrivial proportion of the area mapped. In addition, because ecotones are ecologically significant and important to conservation, the portrayal of transitional space between communities is worth consideration in the future creation of vegetation maps within California.