While there are no safety harnesses to accommodate a car seat in the Wonderfold, the sides are high enough to prevent a car seat from falling out. However, this is a personal preference for most parents. It may not be the best idea to have an unsecured car seat inside if you’re enduring heavy terrain. Many parents claim that they remove one of the seats to accommodate their infant seat, and their older children can still sit on the other seat with no problems.