The maturity principle: how people change through adulthood

What is the maturity principle?

The maturity principle is the steady pattern in how average personality levels move across adulthood: more dependable, calmer under pressure, more considerate. A meta-analysis of ninety-two longitudinal samples found Conscientiousness and Emotional Stability rising, steepest between about 20 and 40, along with social dominance, the assertive half of Extraversion. Agreeableness moved mainly later in life. Social vitality, the sociable half of Extraversion, and Openness to Experience rose in adolescence, then declined in old age (Roberts, Walton & Viechtbauer, 2006).

These are averages across large samples, so a person can hold steady, drift the other way, or move faster than the group, and the sizes are modest, a nudge across a decade rather than a different person.

What does the cross-sectional evidence show?

The meta-analysis above followed the same people over time. A separate line of evidence compares different people at different ages within one large sample, and points the same way. A study of 132,515 adults aged 21 to 60 found Conscientiousness and Agreeableness increasing throughout early and middle adulthood, well past the age either trait was once assumed to have finished moving (Srivastava et al., 2003).

That study tested a specific claim, that personality is set like plaster by 30 and does not move again. The data did not support it. Neuroticism, the inverse of Emotional Stability, declined with age among women in the sample but showed no reliable change among men, a reminder that the maturity principle has exceptions (Srivastava et al., 2003).

Do life events and roles drive the change?

A panel study followed 14,718 German adults and found personality moving at almost every age, with a curved relationship between age and average trait levels. The study also found personality predicting which major life events people went on to experience, then shifting in reaction to them, with effects specific to the event rather than a general softening (Specht et al., 2011).

The more persuasive account is about roles rather than single incidents. A first job, a partner, a child or the care of an ageing parent changes what is asked of a person daily, and a trait is close to the residue of daily behaviour. A role that rewards showing up on time works like a slow, unplanned intervention on Conscientiousness. The arrow runs both ways, though: traits shape which jobs and partners a person meets, so change after an event is not proof the event produced it.

Can traits be changed on purpose, or only observed?

Everything so far describes averages, not choices. One influential review argues for treating traits as both durable predictors of how a life tends to go and as targets for deliberate change, against the older assumption that they are fixed, though such change is harder than most typical intervention targets (Bleidorn et al., 2019).

The rise in Conscientiousness and Emotional Stability is not evidence that nothing a person does matters. It is a strong average current most lives get carried by, and moving faster than it is a separate question, covered on can personality change.

How does rank order stability fit alongside average change?

Average levels moving is one kind of change. Rank order, whether the people who scored highest keep scoring highest, is a different question. A meta-analysis of 152 longitudinal studies, pooling 3,217 test-retest correlations, found rank-order consistency rising steadily with age: about .31 in childhood, .54 in the college years, .64 at 30, and a plateau around .74 between 50 and 70 (Roberts & DelVecchio, 2000).

Put the two findings together and the maturity principle is easier to picture. Most people drift toward more Conscientiousness and Emotional Stability at roughly the same pace, so a person ahead in their twenties is often still ahead in their fifties, even though everyone has moved. High rank-order stability is not the same as no change; see mean-level change versus rank-order change.

What does this mean for you at 25 versus 55?

At 25, a middling score on Conscientiousness or Emotional Stability is unremarkable, and the average path over the next two decades runs upward rather than down. Reading a young adult's percentile as a fixed verdict misreads the number: the group average keeps climbing, and this reading is an early snapshot.

At 55, the same percentile carries more weight, since most of the age-related rise has already happened generally, so a below-average score is harder to explain away as youth. Agreeableness is the exception: its largest movement shows up in old age rather than earlier, so a modest score at 55 sits closer to that trait's own timeline. See how personality changes with age for more.

How does Wellington measure this?

Wellington is a science-based personality assessment from Therabot Labs LLC. It measures personality as continuous traits, built on the Big Five and HEXACO models, and writes the results back as a personal report rather than a type.

The free Snapshot asks 60 questions and scores 6 dimensions: Extraversion, Agreeableness, Conscientiousness, Emotional Stability, Openness to Experience and Honesty-Humility. The first ten questions are answered before anything is asked; after question ten you sign in with an email address so your answers are saved. There is no card. Every trait is reported as a percentile against the reference sample. The three bands, Quiet below the 30th percentile, Balanced to the 70th, High above, and the Portrait names exist to make the result easier to talk about; the percentile is the measurement, always shown alongside. Norms are provisional, and a percentile compares you with adults generally rather than adults your age, worth remembering given how much movement this principle describes in the twenties and thirties.

The Wellington Membership, $4.99 a month, reaches 90 traits including every Big Five facet, and adds a weekly module toward all 255 traits, with retests in year two. Wellington is a wellness tool for reflection, not a medical or psychological diagnosis, and it does not replace care from a qualified professional. It is not for hiring, and you can export or delete your data at any time.

Questions people ask

Does the maturity principle apply to everyone the same way?

No. It describes an average across large samples, and individuals vary around it. One large study found Neuroticism declining with age among women but not men, and some people move faster than the group, hold steady, or drift the other way (Srivastava et al., 2003). Treat the pattern as a typical direction, not a forecast.

At what age does the maturity principle stop?

It slows rather than stops. Rank-order stability rises through adulthood and plateaus around age 50 to 70 (Roberts & DelVecchio, 2000), and Conscientiousness and Agreeableness kept rising through early and middle adulthood in a large sample of 21 to 60 year olds (Srivastava et al., 2003). Agreeableness has its own later timeline, moving mainly in old age (Roberts, Walton & Viechtbauer, 2006).

Why do people get calmer as they get older?

The leading account is role demands rather than age itself. Work, partnership and caregiving ask for reliability every day, and daily behaviour is what a trait is made of. A panel study of 14,718 German adults found personality shifting in reaction to major life events (Specht et al., 2011), though traits also shape which roles people take on.

Is the maturity principle the same as saying personality never changes at an individual level?

No. The maturity principle is about average levels moving in a shared direction. Rank-order stability, whether the highest scorers stay highest, is a separate finding that rises with age without reaching 1.0 (Roberts & DelVecchio, 2000). Average movement and lasting individual differences can both be true at once.