Paleoecological studies from tropical islands worldwide show that human colonization has transformed these remote biotic communities.  Island histories reveal that human predation and human-mediated landscape change have each played a key role, but many extinctions following human arrival are strongly associated with aliens -- introduced predators, herbivores, weeds, and diseases.  Kaua`i is an interesting case in which a human-caused extinction catastrophe is currently occurring in a microcosm of island endemics.  Recent formal reviews of the status of 21 Federally listed endangered plant species carried out by the National Tropical Botanical Garden (NTBG), under contract to the US Fish and Wildlife Service, provide opportunities to evaluate the effectiveness of conservation programs for these species carried out under the Endangered Species Act.  These and other results suggest that conventional in situ and ex situ conservation strategies have been insufficient for many of the rarest endemic Hawaiian plants.  However, paleoecological findings support the idea that creating new populations in formerly much larger late prehistoric and early historical ranges of declining species may provide a reliable and cost-effective hedge against extinction.  On Kaua`i, several paleoecological sites have played key roles in planning and implementing adjacent ecological and cultural restoration projects.  Inter situ restorations, in which rare native species are conserved by creating new populations within the historical or prehistoric range, have shown initial success on properties of the NTBG and collaborating landowners.  In particular, the Makauwahi Cave Reserve on Kaua`i is an innovative prototype for this rewarding collaboration between paleoecologists and inter situ restorationists.