able human beings to explore and learn about the world around us emerge and become remarkably sophisticated. The child becomes a social being with an array of deeply important relationships. Language is acquired and powerful communicative capacities develop. And, the child's emotional repertoire and awareness grow to encompass both tremendous joy and deep sadness. The tasks to be accomplished range from developing day-night rhythms to acquiring a rudimentary moral code to learning how to negotiate and sustain friendships.
At the same time, virtually no one argues that a given child's life course is set by the time of school entry. People are not like rockets whose trajectory is established at the moment they are launched. Indeed, it is the lifelong capacity for change and reorganization that renders human beings capable of dramatic recovery from early harm and incapable of being inoculated against later adversity. This lifelong plasticity renders us both adaptive and vulnerable.
Development depends on both stability and flexibility—it is not a zero-sum game that sets the importance of the early years against the value of the later years. The real question is not which matters more—early or later experience—but how is later experience influenced by early experience? This directs attention to the early childhood years not because they provide an unalterable blueprint for adult well-being, but because what is learned at the beginning of life establishes a set of capabilities, orientations to the world, and expectations about how things and people will behave that affect how new experiences are selected and processed. The infant who has learned that he can engage his parent in play and make objects do what he wants them to do acquires a fundamental belief in his ability to affect the world around him. The toddler who has learned that the people she depends on for comfort will help her when she is distressed is more likely to approach others with empathy and trust than the toddler whose worries and fears have been dismissed or belittled. The preschooler who has routinely cuddled into an adult's lap and read books before going to bed is more likely to enter kindergarten with a keen interest in reading. The child who has missed these experiences may have a hard time recapturing them later in life. In short, getting off to a good start in life is a strategy for increasing the odds of greater adult competence.
What do we know about how many young children are getting off to a good start? It would seem logical in a report of this nature to include information about trends in the well-being of young children. In fact, as a nation, we have surprisingly little information of this nature. We know far more about trends in the conditions, such as poverty and use of child care (see Part III), that affect young children than we do about the children themselves.
The data that are available present a very mixed picture (for an excel-