halfway house

from The American Heritage® Dictionary of the English Language, 5th Edition.

• noun A rehabilitation center where people who have left an institution, such as a hospital or prison, are helped to readjust to the outside world.
• noun A stopping place, such as an inn, that marks the midpoint of a journey.

from the GNU version of the Collaborative International Dictionary of English.

• an inn or place of call midway on a journey.
• A residence for former convicts, persons recovering from mental illness, or from drug or alcohol addiction, serving as an intermediate environment between total confinement and complete freedom, and having structured programs designed to ease successful reintegration into society.

from Wiktionary, Creative Commons Attribution/Share-Alike License.

• noun A temporary residence for those who have left prison, residential drug rehabilitation, or the like, designed to ease them back into society.