  Electroweak symmetry can be naturally broken by observed quark and gauge
fields in various extra-dimensional configurations. No new {\it fundamental}
fields are required below the quantum gravitational scale ($\sim$ 10 - 100
TeV). We examine schemes in which the QCD gauge group alone, in compact extra
dimensions, forms a composite Higgs doublet out of (t,b)_L and a linear
combination of the Kaluza-Klein modes of t_R. The effective theory at low
energies is the Standard Model. The top-quark mass is controlled by the number
of active t_R Kaluza-Klein modes below the string scale, and is in agreement
with experiment.
