Personal boundaries are necessary for psychological stability. Such boundaries must be at once impermeable enough to provide a person with a consistent sense of self-sameness, and porous enough to incorporate new experiences that contribute to growth. A developmental model is proposed that suggests that neglect in early life produces porous boundaries, such as those of the borderline personality. Conversely, intrusiveness can lead to the establishment of overly rigid boundaries, typically found in paranoid and narcissistically disturbed individuals. The author discusses