Mentors and mentees alike agree that mentorship is an effective way to learn. So why, according to the Association for Talent Development, do just 29 percent of workers have access to a formal mentoring program?

The trouble, unfortunately, is that many companies see mentorship as a private matter. Despite the fact that ATD’s survey showed that nearly six in 10 talent development professionals think mentoring achieves development goals, the most common type of workplace mentoring is informal. At those organizations, mentoring relationships tend to be unstructured, inconsistent, and less accessible.

Especially in today’s cutthroat talent environment, companies can’t afford not to invest in robust mentoring programs. LinkedIn data published last year showed that 94 percent of employees would stay with a company longer if it invested in their training and development. Formal mentoring creates more valuable employees, less turnover, and stronger team relationships.

Make More of Mentoring

How, exactly, do firms create mutually beneficial mentorship programs? To bring mentorship to life at your company:

1. Focus on the fit.

For better or worse, the way we like to learn heavily influences the way we teach. Before pairing mentors and mentees, sort them by their preferred learning style. Nonprofit Education Planner offers a free self-assessment tool that, while geared toward school-age students, works for the workplace as well.

In addition to learning styles, consider individual chemistry. The Midland Institute for Entrepreneurship, which provides teenagers with entrepreneurial education via its CEO program, matches community leaders with students through a “speed dating” activity. Mentors and students then list their top three matches, ensuring each participant is paired with someone he or she wants to be around.

2. Encourage affinity groups.

One of the greatest misconceptions about mentoring is that it only works with one-on-one relationships. But social learners, in particular, learn best from like-minded communities. What’s more, affinity groups give participants practice in both mentor and mentee roles, which can help workers in traditional mentoring relationships relate better to their counterpart.

International consultancy Bain & Company is a major proponent of this type of mentorship. Company-sponsored groups like Blacks at Bain, Women at Bain, Veterans at Bain, and LGBTQ group BGLAD provide their members with resources, connections, and professional development opportunities above and beyond what many junior-level employees would otherwise receive.

3. Include external hires.

More than one-fifth of jobs in America are now held by contingent workers, according an NPR/Marist poll published last year. Within a decade, contractors and freelancers may well make up half of the U.S. workforce. Even more than traditional office workers, those individuals need access to the training and connections that peer mentorship provides.

Whenever possible, pair internal and external team members. Ent Credit Union does so with EntRANCE, a two-year initiative that gives participants experience with the lending side of its business. The program helps Ent’s full-time team collaborate more effectively with its contractors, while external team members gain skills in consumer lending, business analytics, and leadership. What’s more, Ent’s leaders who participate in the program help contractors map out their career path.

4. Make executive participation mandatory.

Whether they intend to or not, executives shape company culture through their choices and actions. When workers see leaders participating in a program, they perceive it as a company priority. By making time for mentorship, executives motivate others to do the same.

Particularly at large companies, where mentorship programs tend to be logistically difficult and cultures slow to change, executive buy-in is essential. Although Boeing has 50,000 employees, its rotational mentorship program has been around for years because participants are paired with a senior- or executive-level leader. For terms of roughly two years, participants get to experience work life in the defense firm’s business, engineering, HR, or IT departments.

Mentoring programs might not be sexy investments, but their importance can’t be overstated. Not only do they cost less than compensation increases, formal trainings, and workspace improvements, but they strengthen the company across multiple dimensions. More engaged employees, better rapport between teams, and less turnover make mentorships a winning way to learn.