Studies suggest that high-latitude plants should be more palatable to herbivores than low-latitude conspecifics. Few studies, however, have examined whether this increased plant palatability indicates better plant quality for herbivores. We worked with three plant species and six associated herbivores along the U.S. Atlantic Coast to examine whether plant quality for herbivores increases with latitudes, and whether herbivores show local adaptation to plants from their own geographic regions. Past studies had shown that high-latitude plants of all 3 species were more palatable to herbivores than low-latitude conspecifics. Our survey on leaf traits generally suggested that high-latitude plants should also have been of higher quality to herbivores. Leaf C:N ratio in all 3 plant species decreased toward higher latitudes, consistent with higher chlorophyll contents at high latitudes in 2 species studied. Leaf toughness decreased toward higher latitudes in 1 species, but showed a hump-shape relation with latitude in the other two. The body size of 4 herbivore species increased with latitudes, consistent with high-latitude leaves being of higher quality, while 2 grasshopper species showed the opposite pattern, likely due to life-history constraints. In the laboratory, plants from higher latitudes supported better herbivore performance for 4 out of 6 herbivore species. The geographic region from which herbivores were collected significantly affected herbivore performance in all 6 species; however, the pattern was mixed. We found no evidence for local adaptation by herbivores to plants from their own geographic region. Our results suggest that more-palatable plants at high latitudes support better herbivore growth, and geographic origin of either plants or herbivores can affect herbivore performance. Given that plants and herbivores are diversified into local populations with different traits, the nature of plant-herbivore interactions is likely to change if climate change “reshuffles” plant and herbivore populations across latitude.