Climate change is the greatest challenge facing all ecosystems on earth. It is expected to have variable effects on ecosystems, with species potentially facing a myriad of environmental changes across their ranges. Mediterranean climates are biodiversity hotspots marked by climate extremes, which will only be exacerbated by climate change. How climate change will affect plants in these ecosystems is an important question to pursue, as it will have implications for future rates of biodiversity. To understand range-wide effects on plants in response to climate change, we must first understand how species’ ranges behave, in particular at range limits, as these are the areas of a species’ range where expansion or contraction will occur. I provide a history of range limits research, an overview of how range limits are studied, and a small review of recent range limits work. Then, using the ecological model organism Erythranthe laciniata, I examined range-wide implications of the 2012-2016 drought in California, which was exacerbated by climate change. I implemented a resurrection study, growing pre-drought and drought generation plants in a growth chamber environment, with four treatments testing for range-wide adaptation to drought, and the potential for adaptation to heat; treatments were based on climate predictions for the Sierra Nevada mountains. I found higher fitness for the drought generation in drought conditions, with a strong decline in fitness in the higher heat treatments in both generations. This study shows that adaptation to drought is possible but may not confer higher fitness in higher heat conditions. Next, in a common garden resurrection study, I tested the fitness of pre-drought and drought generation plants from low, central, and high elevation populations in a reciprocal transplant experiment. The drought generation had higher fitness at the high garden, with the two generations having similar fitness at the central and low gardens. I found evidence of local adaptation in the high populations, while the low elevation populations had the lowest fitness in all gardens. This study shows limited adaptation to contemporary conditions, with the drought generation in the high garden showing the strongest adaptive response. Finally, to understand how adaptation may vary across species’ ranges, I and my collaborators performed a literature review and meta-analysis of range-wide quantitative genetic variation (QGV) studies. It has been theorized that QGV, and therefore adaptability, will be highest at the center of a species geographic and/or niche range, but we found little evidence to support this. This study highlights the need for more research into QGV variation across specie’s ranges. Taken together, my dissertation work emphasizes the importance of understanding range-wide patterns of adaptation to climate change.