In the 1970s, there began to be a realization that parks, monuments, and other recreational areas were not visited by people from minority racial and ethnic groups in proportion to their representation in the U.S. population. Parks personnel realized that the demographic trends in the U.S. would accentuate the problem in the decades to come. They worried that, as traditional white, middle-class visitors became less dominant in the population, support for parks would erode. Further, if the intention is to have Americans be ecologically and historically literate and parks are to be an important part of that effort, the lack of visitation by other racial and ethnic groups will mean a significant part--maybe a majority--of the population will lack that literacy. Social scientists studied the problem throughout the last third of the 20th century. While initial studies worried that racial and ethnic minorities didn't have the same concern for the environment as the dominant white culture, later studies showed the fallacy in those early findings. At the end of the 20th century, Floyd (1999, 2001) wrote about the four major theories in the literature that attempted to explain reasons for low visitation rates to parks and other wild settings among racial and ethnic minorities. The theories explaining such non-use included: 1. the marginality hypothesis (groups lack the resources to participate socially, from past discrimination, and economically); 2. the subcultural hypothesis (racial and ethnic groups have different value systems and socialization practices that preclude some from participation in outdoor recreation, independent of socioeconomic factors); 3. assimilation theory (the degree to which a group is assimilated into the dominant society--acculturated--is reflected in their park use); and 4. discrimination hypothesis (park use is affected by actual or perceived discrimination, past discrimination, and institutional discrimination, both real and perceived). Studies of various sub-groups and cross-cultural studies continued throughout the first decade of the 21st Century. While the marginality hypothesis has gained prominence, all four of the explanatory theories have proven to be explanatory for some groups in some locations at some times. The barriers that prevent many underserved groups from using parks, monuments and other recreation areas have been identified. Roberts summed them up well in her 2007 paper: 1. access limitations (including transportation or lack thereof, costs, and fear of the outdoors); 2. communication challenges (including language barriers of printed materials, signs, etc.); 3. fear of discrimination (cultural, actual verbal and non-verbal messages from other visitors, overwhelming posted park rules, signs and brochures not reflective of their culture/race); 4. lack of knowledge, experience, awareness (what to do, where to go, how to get there, equipment needed, etc.); and 5. lack of diversity on staff (their group is not represented on staff or only in janitorial or maintenance positions). While research is continuing to sort out the reasons, more attention is being paid to solving the problem. Potential solutions remain difficult, but are possible and are suggested by many authors. They include possible solutions that address each of the major barriers above. In sum, they involve beginning the hard work of changing the culture of the parks, monuments, and museums, moving organizations to become a part of the larger community contexts in which they reside, and engaging those communities. While each park, museum, historic site, aquarium, nature center, etc. is unique in its geographical context, all can benefit from introspection, examining their unique strengths, the audiences they serve and don't serve, and how to become relevant and valued by a true cross-section of the communities in which they exist. It involves learning more about the multi-cultural context in which the site exists, valuing that context, forming authentic partnerships, and being open to change. It will cost money to modify the variety of media utilized in these settings and to mentor and change staff. It will mean, no doubt, a great deal of discomfort for many people. Change is like that. In the end, however, parks, monuments, and museums will be better for it, as will the broader spectrum of people who will come to visit. This review includes articles from peer-reviewed journals primarily from the years 2000 through 2010, some non-peer-reviewed journals that interpreters read regularly, some conference proceedings, and some technical reports. Also included are some articles from prior to 2000 to add some historical perspective. Chapters from books relevant to the topic also are reviewed. While this review does not include every relevant article published, it hopefully gives the reader a sense of the current state of the profession with regard to serving underserved racial and ethnic audiences. [ABSTRACT FROM AUTHOR]