Boston Medical Center is embarking on a significant new initiative to tackle one of its patients’ most daunting problems: a lack of stable housing.

One in four patients admitted to the hospital is homeless, and even more live in unsafe places or are at risk of being evicted — conditions that research shows can exacerbate health problems.

Now, the hospital is tackling the problem by investing $6.5 million over five years in a variety of affordable housing projects throughout Boston. BMC is not building its own housing but partnering with other organizations, such as shelters and community development corporations, and paying them to renovate or build homes.