Young adults between the ages of 18 and 21 go through a lot of life changes and challenges — from job-seeking, to starting college, to finding a romantic partner.

Depression is not uncommon among teens and adults in their early 20's. Yet some members of this group are happier than others in this stage of life.

What's their secret? A new study reports that the happiest young adults are those who maintain good friendships.

The study, which included 1,073 young, single, American adults between the ages of 18 to 24, was led by happiness researcher Lisa Walsh of the University of California, Los Angeles (UCLA). Her survey looked at five key indicators of happiness: friendship, family satisfaction, self-esteem, neuroticism and extraversion.

The number one driver of joy was close friendships.

In general, happier respondents had better physical health and lower levels of depression and anxiety, but the number one driver of joy was close friendships.

“One of the standout findings from our study is how deeply friendships shape happiness for single emerging adults,”the authors said in a press release. “We found that singles who were satisfied with their friendships tended to be happy with their lives, while those dissatisfied with their friendships were less happy. In short, the quality of your friendships is a key factor for your wellbeing, especially if you're single.”

More research is needed to clarify whether friendships caused happiness or whether the two were just correlated, but based on their findings, the authors suggest that young, single adults make it a priority to forge meaningful, long-term friendships.

“The message we hope young people receive is that you don't need a romantic partner to be happy, but you do need satisfying social relationships with other important people in your life like friends and family,” Walsh said in a press release. “Our findings highlight the importance of friendship for wellbeing, especially if you're young and single.”

What's the best way to create and maintain close friendships? The American Psychological Association (APA) offers this advice:

  • Assume people like you. One study showed that when people are told to assume others like them, they become warmer and friendlier. It's known as the “acceptance prophecy.”
  • Aim for intimacy. People who welcome emotional closeness are more likely to form strong friendships.
  • Learn to listen. People feel closer and more connected when they know they're being heard.
  • Be consistent. Close friendships require investing in your relationships over time and often requires practice.

The study is published in PLOS ONE.