  We study the emergence of collective scattering in the presence of
dipole-dipole interactions when we illuminate a cold cloud of rubidium atoms
with a near-resonant and weak intensity laser. The size of the atomic sample is
comparable to the wavelength of light. When we gradually increase the atom
number from 1 to 450, we observe a broadening of the line, a small red shift
and, consistently with these, a strong suppression of the scattered light with
respect to the noninteracting atom case. Numerical simulations, which include
the internal atomic level structure, agree with the data.
