If it's Tuesday, it must be Sarah. Those placing a call to Harcourt's children's publicity department in San Diego will find that Sarah Shealy picks up the phone on Monday, Tuesday and Wednesday mornings. For the remainder of the week, callers will get Barbara Fisch on the line.

Since October of 1993, the two have been sharing the job of senior publicist in an arrangement that everyone--from this duo themselves to the company's top brass--agrees runs so smoothly that it could well serve as a model for any human resources department. Not to mention, as Fisch pointed out, "This is a relationship that has lasted longer than many marriages."

The two women's paths first crossed in 1989, when Shealy, newly married, moved to California from Boston, where she had worked in children's marketing at Houghton Mifflin while attending graduate school. Louise Pelan, now v-p and publisher, Harcourt Children's Books, hired her as special promotions manager.

Fisch, meanwhile, had begun working at Harcourt in 1982, initially as a secretary and for four years after that in sub rights. She was laid off in 1987, when the company was in the thr s of fighting a takeover bid by Robert Maxwell, but returned in 1990 when her job was reinstated. "About a year later, the children's marketing director left the company," Fisch recalled, "and Louise asked me if I would consider stepping into that position. Sarah was in the department at that time, and that was the beginning of our working together."

But this chapter soon ended. After Shealy returned from maternity leave in 1992, following the birth of her first child, she decided that she wanted to work part- rather than full-time. This idea didn't fly with Pelan, who was dismayed at having to turn down Shealy's request. "I just didn't see how we would be able to find a qualified person to fill the other part of what was a very full-time job," she explained. "So I had to say 'no,' which I hated to do."

When Fisch returned from maternity leave after the birth of her first child in 1993, Louise informed her that she had been given the go-ahead to add an extra person to the children's marketing department, and suggested that Fisch consider restructuring. "A light went off in my head," Fisch recalled. "When Sarah left the company, she had said, 'Well, maybe we could share a job at some point,' but I thought at the time, 'That's definitely not for me.' But now I thought perhaps we could create a job we could do together and continue to work while spending time with our children. The two of us met at a Chinese restaurant and wrote a memo proposing a job-sharing arrangement, which we submitted to Louise the next morning."

The egg rolls apparently provided just the right inspiration. "I knew Barb and Sarah both very well--and knew the quality of their work," Pelan said. "There was no such setup in any other department at Harcourt, but it sounded like a wonderful idea, so I said, 'Let's give this a try.'"

It was a risk worth taking. Fisch and Shealy, who share an office, an assistant and the all-important "basket," appear to work as a single, highly efficient employee (coincidentally, they're even the same age). Their time in the office overlaps a bit on Wednesdays, when they have a chance to swap information. On their desk sits the basket (which began as a folder but has since expanded in capacity), which holds copies of all correspondence that the person on duty has sent in the other's absence. And each sends a copy to the other of any e-mails she transmits on her watch.

Though Fisch noted that she and Shealy have discovered that it works best for one of them to "own" a particular publicity campaign, each relies on input from the other on any given book project. "And we both bring something to the job that the other d sn't," she mused. "Sarah is a great writer and has a wonderful sense of humor. My experience is more in the administrative and the budgetary areas." ("Thank God for that!" Shealy quipped.)

Their arrangement is viewed favorably both in and out of the company. "Working with Barbara and Sarah is efficient and pleasurable," reported Eden Ross Lipson, children's book editor of the New York Times. "Not only are they unceasingly cheerful, but when I leave them a message at the end of the day on a Tuesday about something that I absolutely need by Thursday, I know with absolute confidence that it will arrive in time."

Both Fisch and Shealy said that their job sharing, which according to Pelan is still unduplicated at Harcourt, and remains rare in publishing in general, is successful largely because the two are so compatible. "I can't imagine doing this with anyone else," Shealy stated. "It's like talking to yourself--but having yourself answer back. It's a perfect situation."