Age is a crucial part of workplace diversity, but learning how to manage across generations is still a challenge. By 2020, we will see five separate generations present in the workplace, which is already creating headaches for HR departments.

How do you cater to millennials--who, according to Ernst and Young, are expected to make up 75% of the workplace by 2025--while simultaneously continuing to meet the needs of the older generations? Gen Z, the generation following millennials (born between 1990-1999), are already showing up to work and believe their ability to work with older generations will set them apart.

Embracing all of these cross-generational differences and making the whole team feel valued is only the starting point for managers. As your team continues to grow, here are helpful ground rules that will keep millennials at a job for more than a year, without pushing baby boomers to an early retirement:

Assign Mentors

Cross-generational meshing can be difficult for teammates to adjust to. In order to close any generational barriers, facilitate mentorship between older team members and younger team members to help encourage interaction and trust within the company.

At Techstars, we host "mentor madness" at the beginning of each accelerator program, where we pair startup founders with experienced mentors in their field. While not always the case, most times the pairings are young founders and older, more-established veterans.

By encouraging these mentor relationships, younger employees will seek out advice from older employees based off their experience and expertise. Millennials prefer real-time feedback, and having an employee they can trust to give it to them straight will help their growth in the company. While on the other hand, older employees will become more open to the fresh perspectives and creative ideas brought to the table by the younger employees.  

Avoid Blanketed Stereotyping

Millennials have the reputation of being unreliable, entitled and lazy. Baby boomers are described as being stuck in their own ways, tech illiterate, and have more traditional outlooks. Assuming a recent college grad will act in this way is already discouraging this employee from creating a name for themselves in the workplace. They can fit the mold you've already created and will look elsewhere to break the mold.

As a manager it can be easy to look at age groups in one blanketed way. Don't mistake these for generational traits. While, yes, each generation may have common tendencies, skill-sets, and attributes, each person brings something unique to the table.

At Startup Weekend in Louisville, the winning pitch was led by a junior in high school. While it could have been easy to dismiss the company pitch as elementary, the student showed everyone at the event that her idea had real potential.  

It's important to make a conscious effort to understand each person's needs and contributions individually rather than generationally as a whole. Those who you manage deserve to be evaluated and listened to for their personal attributes and will become resentful if they realize they're being managed as a group based off the year they were born.

Give Equal Opportunity

Give all employees equal opportunity to voice their opinions. It doesn't matter if an employee is just out of college or has been with the company for 10+ years. It's important to provide everyone with a forum to present creative thoughts, concerns, ideas and complaints.

One of my favorite books is "Team of Rivals", which describes how President Lincoln filled his cabinet with political rivals in order to increase the number of diverse viewpoints. That's how I feel about the people surrounding me. By creating an inclusive environment in which everyone feels heard, you make better decisions.

By giving everyone equal opportunity to participate, the different generations will begin to listen to and appreciate others thoughts and expertise.

Adjust Communication Methods

As a manager, it's crucial to encourage open communication. However, not everyone prefers the same style of communication. It's important to discuss each individual's preferred method of communication early on in your working relationship. This will ensure that they are getting the guidance they are looking for.

Our organization uses a handful of different communication tools to cater to various employees. With email being a staple, we also discuss initiatives and tasks through Slack, collaborate using Google Docs, send one-off voice messages using Voxer, share each-other's work on Twitter and host meetings, both in-person and via video chat, so we can capture the needs of everyone's communication preference.

Communication style is another thing that tends to vary from generation to generation. Baby boomers and the more senior employees may prefer to communicate face to face or via phone call rather than digitally. Millennials and post millennials have grown up having constant lines of communication with friends, family, and colleagues. So they may prefer communicating via email, instant message or text rather than in person.

I have employees that are in the 20's and their 60's, with everything in between. Listening to all the diverse viewpoints and sets of experience helps make us stronger.