Share and share alike: job sharing can boost productivity and help retain vital workers, but it can't work effectively without help from HR. If job sharing were a category in the collection of "Guinness World Records," top honors might go to Charlotte Schutzman and Sue Manix. The two women have shared many jobs during 16 years, surviving two corporate mergers and a relocation while earning two promotions in the process.

Currently, Schutzman and Manix share the post of vice president of public affairs and communications at New York-based Verizon Communications Inc. Each works two days a week and on alternate Wednesdays. They talk by phone at least twice a week, and their close partnership has enabled them to stay on track professionally while raising their children--Manix has three, Schutzman has two.

 "It's been good for us, it's been good for the company," says Schutzman. "If we didn't job-share," she says, "we might have left." Instead, Verizon gets to keep two experienced employees on the payroll...