Some buildings try hard to balance the needs of different populations, even on a tight budget.

Grassroots efforts to serve this exploding population — the first wave of baby boomers has already turned 65 — range from help buying groceries to informational programs on the complexities of Medicare. And they win enthusiastic praise.

“These programs present challenges,” said Fredda Vladeck, the director of the Aging in Place Initiative of the United Hospital Fund and creator of the city’s first government-funded NORC program, at Penn South, an income-restricted co-op in Chelsea. “But there’s no question that they can have a profound effect on the quality of life for older people, by helping them stay in their homes for as long as possible, as well as having a positive impact on the overall community. And that’s a huge public benefit.”

One of the earliest examples of a privately run program was created at Lincoln Towers, a cluster of beige brick high-rises in the West 60s that is home to more than 9,000 people in 4,000 apartments. Built as a rent-stabilized complex in the 1960s, the buildings went co-op in 1987. Project Open, which grew out of the Lincoln Towers tenants association, was born three years later. Janice Hohenstein, who moved into 170 West End Avenue on Aug. 1, 1965, the day it opened, and will be 92 come July, was one of the two founders.

Some 40 percent of Lincoln Towers’ residents are over 60; some are in their 80s and 90s. Many are single and live in the starter units to which they moved decades ago. The group’s Web site suggests the range and intensity of their concerns: “Who will help me in an emergency?” “I’m alone most of the time, my spouse, my friends are gone.” “My bills get more and more confusing and overwhelming.”