developing and motivating his 44 employees. "Every time we've done an employee survey, mentorship has popped up as an interest and a need," says the president and CEO of San Francisco-based national independent communications firm Allison & Partners.

Allison's appreciation for mentoring dates to the early days of the 4-year-old company. Back then, however, the firm didn't have enough resources to establish a formal mentoring program; there weren't enough senior people to supply mentors to everyone who was interested. Allison decided to allow for informal mentoring, where employees got to choose their own mentors. That method, he figured, made the most of the mentoring resources he had. The approach worked well enough that today, even though Allison has enough senior employees to designate mentors, he still uses the voluntary program.

Mentoring's value is well-established. It helps recent hires acclimate to corporate culture, and it allows experienced workers to pass on their accumulated expertise. Mentoring also benefits mentors and aids in succession planning.

There is more than one way to mentor an employee, and one of the major divergences is between programs that select and assign mentors to individual employees and those that let employees choose their own mentors. Bigger firms generally assign mentors. Some even use computerized mentor-matching systems, an approach that is faster and more objective than more personal techniques.

Allowing employees to pick their own mentors has some important advantages. In addition to being a good solution for resource-constrained small firms like Allison & Partners, self-selection helps ensure a good fit between mentor and mentee, says Twyla Cummings, a professor at Rochester Institute of Technology in Rochester, New York, and a mentoring expert. "Personalities have to fit," she stresses.

Self-matching also allows employees to tap external resources. Allison was stumped by one employee's request for a female mentor. "When she described the person she wanted as a mentor, I didn't feel we had a person like that in the company," he says. Allison introduced the employee to a woman he knew from an entrepreneurs group, and the two agreed to establish the mentoring relationship.

When mentors are assigned, each mentor is typically matched with only one person. When mentors are selected by employees, however, it's not unusual for a single mentor to be seen as an attractive advisor by more than one person. This can help maximize the value of a company's most effective mentors, says Allison.

Self-selection may have risks and limits as well. Employees may pick the wrong mentors, says Rene D. Petrin, president of Chestnut Hill, Massachusetts, mentoring consulting firm Management Mentors Inc. Optimally, a mentor is someone who can help an employee acquire the skills, contacts and knowledge necessary to reach long-term career goals, Petrin says. That's not necessarily the person an employee will select.

"Employees tend to look at the person who's most powerful, and who they know, instead of broadening their thinking to include where they want to go, what they need and who is the best person that can help," Petrin says.

Training can help. Educate employees on what makes a good mentor, what mentoring can do for them, and how to make the most of the relationship. Experts also advise training mentors, which Allison plans to start doing soon.

However informal or well-organized your mentoring effort, make sure you don't discourage the spontaneous mentoring relationships that spring up when a veteran employee voluntarily decides to take someone under his or her wing. Says Cummings, "That's mentoring at its best and strongest."

Mark Hendricks writes on business and technology for leading publications and is author of Not Just a Living.