Mixed-Use Development
Jacobs advocated for "mixed-use" urban development - the integration of different building types and uses, whether residential or commercial, old or new. According to this idea, cities depend on a diversity of buildings, residences, businesses and other non-residential uses, as well as people of different ages using areas at different times of day, to create community vitality. She saw cities as being "organic, spontaneous, and untidy," and views the intermingling of city uses and users as crucial to economic and urban development.
Bottom-Up Community Planning
Jacobs contested the traditional planning approach that relies on the judgment of outside experts, proposing that local expertise is better suited to guiding community development. She based her writing on empirical experience and observation, noting how the prescribed government policies for planning and development are usually inconsistent with the real-life functioning of city neighborhoods.
The Case for Higher Density
Although orthodox planning theory had blamed high density for crime, filth, and a host of other problems, Jacobs disproved these assumptions and demonstrated how a high concentration of people is vital for city life, economic growth, and prosperity. While acknowledging that density alone does not produce healthy communities, she illustrated through concrete examples how higher densities yield a critical mass of people that is capable of supporting more vibrant communities. In exposing the difference between high density and overcrowding, Jacobs dispelled many myths about high concentrations of people.