 15. Personality Development in Adulthood and Later Life  343
behaviors in parents in ways that are often 
unexpected. Other events, such as natural 
disasters and wars, present an even greater 
challenge to the ability of individual person -
ality traits to shape contexts. As Abraham 
Lincoln (2001) said in 1864, “I claim not to 
have controlled events, but confess plainly 
that events have controlled me.”
Lest we sound like radical behaviorists, 
we reiterate that the weight of the evidence 
shows that personality characteristics play 
a major role in the selection of people into 
contexts, how they behave once they are in 
in such contexts, and how they ultimately 
change or grow as a result of being in a 
given context (e.g., Jackson, 2011; Kandler, 
Zimmermann, & McAdams, 2014). Yet the 
context retains some independence from 
the person, too. Thus, it remains useful for 
personality development researchers to con -
tinue carrying out studies of predictors of 
personality change.
Personality Change as a Predictor
Does change in personality itself predict 
outcomes we care about (Mroczek, Spiro, 
Griffin, & Neupert, 2006)? This is more 
than an academic question given the impor -
tance of personality traits for a considerable 
array of consequential life outcomes, such 
as earnings and net worth, relationship suc -
cess, educational attainment, health, and 
longevity (Allemand et al., 2019; Allemand 
& Flückiger, 2017; Ozer & Benet-  Martinez, 
2006). Much of the interest in interventions 
is driven by the possibility of altering these 
personality-  predicted outcomes.
A small number of researchers has looked 
at naturally occurring personality change 
and used that change as a predictor, in and 
of itself, of later outcomes. Such a study re -
quires a unique longitudinal design (Mroc -
zek et al., 2006). Enough measurement occa -
sions on a personality characteristics on the 
front end are needed to carry out trajectory 
models (latent growth or multilevel change). 
Then, outcome measurement needs to occur 
after all or most of the personality measure -
ment occasions. It is often desirable to have 
least some temporal separation between the 
end of all or most individual trajectories and 
the occurrence of the outcome (which can happen at different times and ages for differ -
ent people). Given these requirements, it is 
not surprising that there are very few stud -
ies of personality change as a predictor, but 
there are some. Mroczek and Spiro (2007) 
documented that MLM-  estimated changes 
in neuroticism, but not extraversion, were 
predictive of mortality risk over an 18-year 
period (increasing neuroticism predicted 
earlier mortality). Steiger et al. (2014) found 
that decreasing self-  esteem in adolescence 
predicts depression in midadulthood, and 
Allemand et al. (2019) found that increases 
in self-  control in adolescence are related to 
better work and interpersonal outcomes in 
middle adulthood. Although this chapter fo -
cuses on adulthood, one additional study is 
worth mentioning. Hampson, Tildesley, An -
drews, Luyckx, and Mroczek (2010) found 
that increasing rates of growth in childhood 
hostility predicted substance use in midado -
lescence.
Other investigations have made use of 
two- occasion studies. Turiano et al. (2012) 
found that increases in agreeableness, ex -
traversion, and conscientiousness over 10 
years were predictive of later self-rated 
health, and that increases in conscientious -
ness were additionally related to few days 
lost to work due to physical health reasons. 
Magee, Heaven, and Miller (2013) found 
that increases in extraversion and conscien -
tiousness were related to better physical and 
mental health, and increases in neuroticism 
were associated with worse physical health. 
These two-  occasion studies do not estimate 
change as well as multiple-  occasions stud -
ies, but often pre- and posttreatment data 
are all that is available. Nevertheless, these 
studies supplement the others with several 
occasions to provide an initial fragment of 
evidence that personality change is associ -
ated with outcomes, sometimes distal out -
comes.
Of course, the bidirectional issues we 
discussed earlier must be considered again. 
To what extent was the mental health out -
come in Magee et al. (2013) already “set 
in motion” before the two assessments of 
personality even occurred? As novel as it 
was, Magee et al. may simply have caught 
a section of a bidirectional process that was 
already in place beforehand, and would re -
main so afterward.