A central question in ecology concerns how some exotic plants that occur at low densities in their native range are able to attain much higher densities where they are introduced.  Houndstongue (Cynoglossum officinale) is a widespread, biennial exotic in western North America, where it grows, on average, at three times the density of native populations in central Europe.  At study sites in Montana (introduced range) and Germany (native range), I experimentally manipulated insect herbivore pressure and created small scale disturbances to determine how these factors affect plant performance in both ranges.  Herbivores reduced plant size and fecundity in the native range, but had little effect on plant performance in the introduced range.  In both ranges, the amount of natural soil disturbance was similar and seedling recruitment responded positively to artificial disturbances.  I combined these experimental results with demographic data collected from populations in both ranges to parameterize integral projection models that forecast long-term population dynamics of houndstongue.  I will report results from these population models, comparing the relative importance of specialist herbivores and small scale disturbances on population size and growth in each range.