Intellectual Disability (Intellectual Developmental Disorder) 35Moderate All through development, the 
individual’s conceptual skills 
lag markedly behind those of 
peers. For preschoolers, lan-
guage and pre-academic skills 
develop slowly. For school-age 
children, progress in reading, 
writing, mathematics, and 
understanding of time and 
money occurs slowly across 
the school years and is mark-
edly limited compared with 
that of peers. For adults, aca-
demic skill development is 
typically at an elementary 
level, and support is required 
for all use of academic skills in 
work and personal life. Ongo-
ing assistance on a daily basis 
is needed to complete concep-
tual tasks of day-to-day life, 
and others may take over these 
responsibilities fully for the 
individual.The individual shows marked differences from 
peers in social and communicative behavior 
across development. Spoken language is typi-
cally a primary tool for social communication 
but is much less complex than that of peers. 
Capacity for relationships is evident in ties to 
family and friends, and the individual may 
have successful friendships across life and 
sometimes romantic relations in adulthood. 
However, individuals may not perceive or 
interpret social cues ac curately. Social judg-
ment and decision-making abilities are lim-
ited, and caretakers must assist the person 
with life decisions. Friendships with typically 
developing peers are often affected by com-
munication or social limitations. Significant 
social and communicative support is needed 
in work settings for success. The individual can care for personal needs involving 
eating, dressing, elimination, and hygiene as an