Before deciding to join his father's public-relations business last year, Eric Samansky spent months weighing some big questions. Did he want to spend so much time with his dad? Could they maintain an amicable father-son relationship and a professional one?

When he joined the firm, Mr. Samansky stumbled onto a quandary he hadn't anticipated: What to call his father, Art Samansky, in a business meeting with clients? "I went to comment on what he said and I thought, 'Oh my God, do I call him Art or Dad?' " recalls Mr. Samansky, who is 33 years old. "I just said, 'As he said.' "

Working with family members presents a host of complexities, from unexpected dilemmas such as what to call dad to agonizing decisions such as whether to fire your sibling. These stresses are surprisingly widespread in American workplaces. Between 80% and 90% of all American companies are family owned or controlled, says Ira Bryck, director of the University of Massachusetts Family Business Center in Amherst, Mass.

As the job market begins to pick up, many of the new opportunities could come from family companies: Most new jobs are created in family-owned or -controlled businesses, Mr. Bryck says. And with the job market still so hotly competitive, many people use family connections to help open doors.

But the decision to take a job with a family member is fraught with complications and emotion. Family tensions can arise even outside the straightforward family-owned-business scenario. Simply working in the same industry as a family member can become awkward. A job where you compete against a family member or spouse at a rival firm can make discussing work at home uncomfortable at best. And people who take jobs at companies where a family member is a top honcho struggle to earn respect.

Career counselors say the most important factor in deciding whether to take a family-related job is whether you really want to work in the business. If you're following a family path because of guilt or laziness, you'll probably end up unhappy.

Piggybacking on a relative's success can backfire too. Damian Birkel, a career counselor for Williams, Roberts, Young Inc. in Winston-Salem, N.C., recalls a former colleague at a department store where he used to work. The man's father was a top executive; the son rose quickly up the ranks. But when the father left during a management shuffle, the son's star fell too.

Jon Leven, son of hotel industry executive Michael Leven, has worked since he was a teenager to prove himself as more than just the boss's son. When Jon Leven, now 38, was in high school, he took some hotel jobs such as working at the check-in desk. "Working with older people in hotels whose initial look at me was, 'OK, here's the boss's kid,' was an invaluable experience," he says. "You eventually gain the trust and respect through your actions. You've got to be careful not to take it personally."

When he began his adult career, he followed his own path. "I really wanted to gain some experience on my own," he says. He worked as a hotel real-estate broker, then moved into restaurant franchising. In 1995, his father and cousin founded U.S. Franchise Systems Inc., a hotel-franchising company based in Atlanta, now owned by the business interests of the Pritzker family. Mr. Leven decided the time was right to join his father. "I always had a very close personal relationship with my father," he says. "I looked up to him and admired him as a leader." Today Jon Leven is the senior vice president of marketing; his father is the chief executive officer.

Early on, Jon Leven learned an important lesson. While negotiating a franchise agreement, he made a concession he wasn't authorized to make. His boss at the time, who wasn't his father, was furious. "I immediately knew it was the wrong thing to do," Mr. Leven says. "I just made the assumption that in our organization, I was making the right decision." He says he wasn't intentionally taking advantage of his family status, but he should have been more aware that his action might be perceived that way. "You have to be on guard not to take liberties," Mr. Leven says. "You go through the channels [and show that] you are a team player."

Mr. Leven also learned to push for honest criticism from his father, who says he finds it difficult to be very tough on his son. The younger Mr. Leven is better with the big picture than the details, for instance, they both say. "With somebody else, I might say, 'You screw up this detail one more time, and you're out,' " Michael Leven says. "You just don't do that in the case of a family member."

But in other important ways, the men enjoy their family ties. The father likes having a candid and trustworthy confidant in his son; the son can ask his father frank questions without worrying about looking stupid. Recently, the two were discussing how to supervise a group of salespeople if that sales force expands. Michael Leven said he would continue to oversee an enlarged group. His son disagreed: Michael Leven wouldn't devote enough time to give them the direct supervision they'd need, Jon Leven said.

Another employee might "be scared stiff" to say something that frank, Michael Leven says. But the younger man was right, they both agree. "I'm not afraid to challenge him, because our relationship is so strong," Jon Leven says.