The authors report an experimental demonstration of electromagnetically induced transparency (EIT) in an ultracold gas of sodium atoms, achieving a light speed reduction to 17 meters per second. The gas is cooled to nanokelvin temperatures using laser and evaporative cooling. A 'coupling' laser beam, propagating at a right angle to the pulsed 'probe' beam, creates quantum interference that allows light pulses to propagate through the medium at a much slower speed than in a vacuum. By cooling the cloud below the transition temperature for Bose-Einstein condensation, even lower pulse propagation velocities (17 m/s) are observed due to increased atom density. The system exhibits large optical nonlinearities, with a nonlinear refractive index of 0.18 cm² W⁻¹, which is of potential interest for quantum optics applications. The experiment involves detailed cooling and trapping techniques, including Zeeman slower and magneto-optical traps, to achieve the necessary conditions for EIT.The authors report an experimental demonstration of electromagnetically induced transparency (EIT) in an ultracold gas of sodium atoms, achieving a light speed reduction to 17 meters per second. The gas is cooled to nanokelvin temperatures using laser and evaporative cooling. A 'coupling' laser beam, propagating at a right angle to the pulsed 'probe' beam, creates quantum interference that allows light pulses to propagate through the medium at a much slower speed than in a vacuum. By cooling the cloud below the transition temperature for Bose-Einstein condensation, even lower pulse propagation velocities (17 m/s) are observed due to increased atom density. The system exhibits large optical nonlinearities, with a nonlinear refractive index of 0.18 cm² W⁻¹, which is of potential interest for quantum optics applications. The experiment involves detailed cooling and trapping techniques, including Zeeman slower and magneto-optical traps, to achieve the necessary conditions for EIT.