As it turns out, walkers interfere with learning to walk. In addition to decreasing the desire to walk by providing an easier alternative, walkers strengthen the wrong muscles. The lower legs are strengthened, but the upper legs and hips become relatively weak. The upper legs and hips are most important for walking. Moreover, children in walkers have more accidents than their counterparts.
Walkers often tip over when a child bumps into a small toy or the edge of a rug.
They are also more likely to take a dangerous fall down a flight of stairs. Along with The American Academy of Pediatrics, I strongly urge parents not to use baby walkers. For children who want to be upright, an exersaucer can be a nice alternative. These look like walkers, but without the wheels. They are safe and developmentally appropriate.