Over the last 15 to 20 years, there have been several major shifts in what researchers, policy makers and practitioners think about what young people need, what they get and where they get it. There have also been shifts in thinking about what young people do, should do and can do and when it is reasonable to expect to see results. These shifts have not been universal — there are still differences among the various theories and strategies proposed and the populations addressed. But shifts have occurred.