Except for monozygotic twins, each person is born with a unique assortment of genes. But one’s genotype, like one’s birth, is only a potentiality. Each of us realizes individuality in the practice of life through the exercise of two systems: the central nervous system, the seat of our psychological self, and the immune system, the adjudicator of our molecular self. These two systems help create individuality because they work to make each of us different from all other persons, including our monozygotic twin. Individuation results from the capacity of these two systems to organize themselves over time in response to the individual’s unique environment. The selforganization of the central nervous system has been dealt with over the years by neurobiologists and cognitive scientists1. Our aim here is to consider the processes determining self-organization in the immune system. In doing this, we shall consider two formative principles: the creation of information and the creation of meaning.