Abstract: A child safety seat which can be mounted on a chair having a seat and a backrest comprises a seat portion which engages the chair seat and includes a child engaging seat part and elongated lateral restraints at the sides of the seat part which extend from front to rear of the seat part. Adjustable length strap means connect at respective opposite ends to the restraints so that adjustment of the strap means effects mutual counter rotation of the restraints to vary the height of the seat part. The safety seat can also be provided with a backrest part which incudes lateral restraints along opposite upright sides thereof. A child safety harness is attached to the safety seat and straps are provided to secure the parts of the seat to the chair seat and backrest. The safety seat is of inflatable form.