The invention relates to a chair which can be used as a chair for adults and as a high chair for a child. The invention addresses the problem of making in both cases an adapted size of the seating available. The chair according to the invention comprises a base (1) having a back rest (4) and a seating (5), said seating (5) being retained on the base (1) so as to be height-adjustable. The seating (5) has a depth suitable for an adult. If the seating is brought into an elevated position, part of it is located behind the back rest (4) so that the effective seating which is in front of the back rest is adapted to the depth required by a child.
