Should an 18 month old baby still have a soft spot on his head?

Yes. The soft spot, or anterior fontanelle, remains open until about age 2 years. This allows the brain to grow freely without waiting for the skull bones to keep up. At 18 months the fontanelle may still be present, may be small, or it may seem closed. As long as the baby's head circumference is growing in the normal range, the fontanelle is fine.