Clinical experience and several long-term studies have shown that fundamental changes in attitude and behavior continue to occur throughout adult life. An understanding of development during middle age helps put into perspective the mystifying and unusual behavior shown by a minority of middle-aged adults. Levinson delineates alternating phases of structure-building periods (six to eight years) with transitional upheavals of four to five years' duration. The latter includes one in the early 40s and again in the 50s. Vaillant emphasizes a career consolidation stage between Erikson's young adulthood (intimacy) and the generativity stage of the 50s. This consolidation stage corresponds in many ways to Levinson's transitional stage of the 40s. Vaillant also makes the point that maturity in midlife is reflected by the changes in the use of more mature adaptive mechanisms (corresponding somewhat to Hamburg's coping behavior) as the adult moves toward the 60s. Development tasks during middle age include adjusting to bodily changes; achieving career goals; readjusting to the marital dyad, adult children, and aging parents; and planning for security in old age.
临床经验和多项长期研究表明，态度和行为的根本变化在成年期会持续发生。了解中年时期的发展有助于正确看待少数中年成年人表现出的令人困惑和异常的行为。莱文森描绘了持续六到八年的结构构建期与持续四到五年的过渡动荡期交替出现的阶段。后者包括40岁出头和50多岁时各出现一次的阶段。瓦兰特强调了在埃里克森的成年早期（亲密感）和50多岁的繁衍阶段之间的职业巩固阶段。这个巩固阶段在很多方面与莱文森的40岁过渡阶段相对应。瓦兰特还指出，随着成年人步入60岁，中年时期的成熟体现在使用更成熟的适应机制（在某种程度上对应于汉堡的应对行为）的变化上。中年时期的发展任务包括适应身体变化；实现职业目标；重新调整与配偶、成年子女和年迈父母的关系；以及为老年生活的保障做规划。
