Paul Baltes's life-span developmental theory includes 6 principles: (1) development is lifelong, involving both (2) gains and losses over time as (3) biological and cultural influences shift, (4) resources are reallocated, (5) development is modifiable, and (6) influenced by historical and cultural context.

1. V.M.WESTERBERG’S SUPER BRIEF THEORY SERIES
PAUL BALTES
BALTES'S LIFE-SPAN DEVELOPMENTAL THEORY
The six principles of Baltes's life-span developmental approach
include the assumptions that:
(1) development is lifelong,
(2) development involves both gain and loss,
(3) the relative influences of biology and culture shift over the life
span,
(4) development involves a changing allocation of resources,
(5) development is modifiable; and
(6) development is influenced by the historical and cultural context.