Pre-adulthood is the high-plasticity period that begins before conception and ends in early adulthood, when lifelong physical and mental traits form within bounds set by nuclear and mitochondrial genetics, heritable prion–protein conformations, and epigenetic states. These traits are critical to vitality, lifespan, and capabilities. The Pre-adult Healthspan Interventions (PHI) initiative catalogs, validates, characterizes, and shares putative Health, Aesthetic, Performance, and Longevity interventions (HAPLI). Augmentive PHI (APHI) goes beyond disaster avoidance to optimize healthspan via early super-salubrious behaviors. Many offer compounding benefits and need no prescription. Modern APHI (e.g., gene therapy) are remarkable, sometimes essential, yet often cost-prohibitive. A large body of APHI research exists, but detailed characterization and implementation is weak, prompting creation of this chapter.