The particular circumstance that sparked a book idea for longtime TV and radio producer turned friendship expert Glenda D. Shaw is a relatable one: About a decade ago, she was at her own birthday party and realized that she wasn’t having all that much fun. “I looked around and thought, these people don’t really support me, and I’m actually somewhat lonely,” Shaw says. The epiphany shook her, as she’d always been someone with a large group of friends. “What I realized was that, by sheer proximity to people, I’d wandered into many friendships—but they weren’t conscious relationships,” she says. To change that, she’s since turned to psychological research to develop a process for sorting and actively engaging with friends, called the four levels of friendship: essential friends, collaborators, associates, and mentors and mentees.

In Shaw’s forthcoming book—Better You, Better Friends: A Whole New Approach to Friendship (out on September 15)—she outlines these different levels of friendship, which she says can help people both understand and classify their relationships.

“Considering the four levels of friendship can help you develop a healthy way to relate to each of your friends and learn to expend energy that you know will be reciprocated.” —Glenda D. Shaw, friendship expert

“Considering the four levels of friendship can help you develop a healthy way to relate to each of your friends and learn to expend energy that you know will be reciprocated,” she says. This allows you to set clear expectations and boundaries around friendships, too, so that each one serves a fulfilling—and not indifferent, or even disappointing—role in your life.

By focusing on your personal approach to different relationships, informed by the different levels of friendship, you can both deepen existing relationships (while removing yourself from unsupportive ones) and embrace new friends in ways that best serve you, says Shaw. Below, she breaks down her framework for the different levels of friendship, so you can align your energy accordingly.

Here are the four levels of friendship, and how each can provide value in your life:

1. Essential friends

This is your core group of close friends, says Shaw, who first identified her essential friends by writing down a set of words that described what she was aiming for in life. “For me, those words were ‘curious,’ ‘visionary,’ ‘encouraging,’ ‘enterprising,’ and ‘purposeful,’” she says. “So I thought about who in my circle would best embrace and support those values, and five people popped out to me.”

These essential friends are your confidantes and the people with whom you share your deepest values. And perhaps most crucially, they’re the ones who loyally stick around, no matter what. “I don’t think you can identify an essential friend without conflict,” says Shaw, “because that’s what creates true empathy.”

We often bury conflict in the interest of maintaining a friendship, but that can bubble up as resentment later on, says Shaw. “Instead, bring the conflict into the conscious mind where you can address it and come to a resolution.” Any friend with whom you can do that easily is more likely to qualify as an essential friend.

2. Collaborators

These are the friends with whom you share an emotional connection at a specific time in your life, says Shaw. “It’s a relationship that requires physical proximity and emotional immediacy in order to function—and while it’s very valuable in a particular context, it becomes less so as that context changes.”

These might be the first friends you met at college or when you moved to a new place. They were a key part of your adjustment process, but perhaps you lost touch with them as you found a new job, or otherwise transitioned to a different stage of life.

While Shaw says that you may have few (if any) boundaries with essential friends—there’s no off-limits topic or issue, and you’re always there when they need support—it’s likely that you do have boundaries (whether spoken or not) with collaborators. For example, you’re likely not scheduling weekly calls, or texting personal news, or hearing the minutiae of their days. Instead, catch-ups are less frequent, and based on the extra time and energy that you have to spare.

3. Associates

Step down a rung on the friendship ladder from collaborators, and you’ll arrive at the associates level. These are the people with whom you’re connected through work or a common interest, passion, or hobby. They serve a particular purpose in providing sociability within those contexts—for example, hanging out with you at an office happy hour, or chatting with you at a book club meeting.

Typically, they’re not the people in whom you’d confide or ask for life advice, adds Shaw. And in most cases, it’s smart to uphold a boundary in that regard, so you aren’t looking for more support or platonic intimacy than the person is willing to give.

That said, because we tend to spend ample time with associate friends in the context of work or hobbies and without many expectations beyond that, there’s a big opportunity to observe their behavior in detail, and assess whether they might move up to the essential level of friendship. “Often, you get to perceive associate friends while they’re at their best, doing something they’re good at or that they love,” says Shaw, “which can give you valuable insight into whether they might turn into essential friends later on in life.”

4. Mentors and mentees

The mentor-mentee relationship is an asymmetrical friendship dynamic, wherein there’s an uneven level of power and control. “With your symmetrical relationships—like your collaborators, associates, and essential friends—you have an equal amount of choice in deciding how and when you’ll hang out,” says Shaw. “With mentors and mentees, typically the mentors are the people who’ve progressed further in life and who have more say as to the depth of the relationship.”

In most cases, mentors are life or career coaches, which might mean they take the form of a manager, or someone else within or outside of your workplace whom you look up to, regardless of their title. “In these relationships, there are very clear boundaries,” says Shaw. Consider how you might not share intimate details about your family or your romantic relationships with your boss, for example. But even so, both parties stand to benefit and learn from these relationships when they function with clear expectations about the time you plan to devote to them, and what you hope to achieve from them, too.

Being the “best” version of a friend to the people in your life at each level relies on self-awareness about how much focus you want and are able to give to each, says Shaw. We all have a finite amount of energy and time, so it’s all the more important to direct it where you’ll find enrichment and fulfillment in return.