In the last two decades of her life, the developmental point of view permeated all areas of Anna Freud’s work. The developmental lines are one manifestation of it. They have both practical and theoretical roles. They can be used by non-analysts as well as analysts to examine a child’s readiness for various life experiences, or to see in detail which necessary capacities are well developed in him, and where there are deficits. They can also be used to pinpoint areas of deficit in adults, and to promote the expansion and modification of theory.