A standard definition of community development often goes something like this:
Community Development is asset building that improves the quality of life among residents of low to moderate income communities, where communities are defined as neighborhoods or multineighborhood areas. 
The million-dollar question in this equation though is, "How do you build the assets (physical, social, human, cultural, financial, and political) of a community in a way that benefits low- and moderate-income residents without displacing them?" Too often development happens in such ways that as a community improves, and demand to live there increases, housing prices inevitably rise. In turn, lower-income residents find it more difficult to find affordable housing options within their strengthening communities. The result being that over time more affluent households end up displacing lower-income residents as they are forced to live elsewhere. The term used to describe this effect is gentrification.
As positive change continues to come to our central city neighborhoods and healthy, stable neighborhoods are the norm, we must ensure that opportunities are created for a diverse group of individuals to live, work, worship, and play in our newly revitalized neighborhoods.
Alan Mallach of the Brookings Institute says this in his paper, Managing Neighborhood Change, about the common gentrifying change that comes to inner-city neighborhoods: