About a half-century ago, Americans seemed to have a fairly clear idea of what it meant to be an adult. They mostly agreed on four criteria: (1) leaving home; (2) working; (3) getting married; and (4) becoming a parent. In 1975, nearly half (45%) of all young adults between the ages of 25 and 34 had already met all four criteria.

The 21st century ushered in a new way of thinking about the meaning of adulthood.

When the Census Bureau asked Americans about the importance of various experiences for becoming an adult, marriage and parenting were no longer important. More than half of the participants (55%) in a nationally representative sample said that getting married was “not important.” The same percentage said that having a child was not important to becoming an adult.

Americans today also accord little importance to living outside of the parental home. Only 26% said that was extremely important to becoming adult, though 56% said it was somewhat important.

So what did matter? Number one on the list was completing formal schooling. Sixty-two percent said that was extremely important to becoming an adult, and 33% said it was somewhat important, for a total of 95% saying it was at least somewhat important.

Having full-time employment was also high on the list. Fifty-two percent said that was extremely important to becoming adult, and 43% said it was somewhat important, adding up to the same total of 95%.

The changing beliefs about what it means to be an adult correspond to changes in how today’s young adults are living.

Compared to the 45% of 25- to 34-year-olds in 1975 who met the four criteria that used to be important (leaving home, working, getting married, and becoming a parent), only 24% of today’s young adults have checked off all four. Almost the same number, 23%, have just two of those experiences: living somewhere other than their parents’ home and having a job.

Getting married and having children used to seem mandatory. Plenty of young adults never thought much about whether they really wanted those things. It is different now. For many more of us, at all ages, how we live our lives is more of a real choice. That’s a good thing.