BENTON COUNTY, Ark.—When Barb Strickert married, she and her husband wrote down a one-year plan for their lives together. And a three-year plan. Five- and 10-year plans, too.

Their meticulous mapping of the future eventually culminated in The Retirement Plan. Barb would leave the corporate world in her early 60s and run a small bed-and-breakfast on their 11-acre wooded plot in the Ozark Mountains. She and her husband, Brian, would convert the garage into a recording studio to promote local musicians.

The best-laid plans of Barb and Brian have gone awry. One bedroom of the would-be B&B, in their walkout basement, is now occupied by Barb’s 83-year-old mother, and the other by her 34-year-old daughter. Barb has reached 64, and, thanks to her new responsibilities, can no longer afford to quit.

“I was hoping to be retired by the age I’m at now,” she says. “That’s not going to happen. I’m going to work until I can’t do the job.”

There is a growing number of baby boomers who find themselves caring for both their elderly parents and their adult children, rather than kicking back at retirement age. They face the strain of constant caregiving and derailed dreams, as well as added expenses. It’s one more reason why many Americans are entering their retirement years as unprepared financially as any generation in years.