<p class="first" id="d962190e104">Adolescence is the phase of life stretching between
childhood and adulthood, and its
definition has long posed a conundrum. Adolescence encompasses elements of biological
growth and major social role transitions, both of which have changed in the past century.
Earlier puberty has accelerated the onset of adolescence in nearly all populations,
while understanding of continued growth has lifted its endpoint age well into the
20s. In parallel, delayed timing of role transitions, including completion of education,
marriage, and parenthood, continue to shift popular perceptions of when adulthood
begins. Arguably, the transition period from childhood to adulthood now occupies a
greater portion of the life course than ever before at a time when unprecedented social
forces, including marketing and digital media, are affecting health and wellbeing
across these years. An expanded and more inclusive definition of adolescence is essential
for developmentally appropriate framing of laws, social policies, and service systems.
Rather than age 10-19 years, a definition of 10-24 years corresponds more closely
to adolescent growth and popular understandings of this life phase and would facilitate
extended investments across a broader range of settings.
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