Section 1 Introductory aspects -- 1. Frailty in pediatrics: definition and care needs -- Section 2 Frail newborn infants -- 2. Premature Infants -- 3. Newborns with congenital malformations -- Section 3 Frail children -- 4. Frail Children with chronic lung disease -- 5. Frailty in patients with chronic kidney disease -- 6. The frail child with chronic liver disease -- 7. The Surgical Management of Children with Intestinal Failure -- 8. Children with obesity -- 9. Frailty in children with oncological disease -- Section 4 Operational improvement strategies -- 10. Operational Improvements in Neonatal Surgery -- 11. Operational improvement in pediatric surgery -- 12. Operational improvement in pediatric neurosurgery -- 13. Fragility of children with severe early onset scoliosis: Description and analysis of innovative techniques with "growing systems" -- 14. Medical and rehabilitation interventions in childrenwith frailty -- 15. Operational improvement in Psycology -- Section 5 Conclusions -- 16. Follow-up to ensure continuity of care and support preventive care -- 17. Social aspects: Sutainability for the patient, the family -- 18. Transitional medicine, from childhood to adulthood.