A light source comprising: a light engine for generating light of one of a plurality of wavelengths, the light engine including: a platform, at least one LED disposed on the platform; an enclosure surrounding a light generating area of the light engine, wherein the enclosure is a bulb-shaped enclosure; a base; a heat dissipating slug including a plurality of radial fins disposed about an outer periphery of the heat dissipating slug, said heat dissipating slug being in thermal communication with said light engine and located on a side of the platform opposite said at least one LED, said heat dissipating slug being inserted into said base; said base and heat dissipating slug being in thermal communication for conducting thermal energy away from the light engine, said heat dissipating slug further transferring heat from the light engine into air; a wavelength converting material to receive light generated by the light engine and convert at least a portion of the received light into visible light, said wavelength converting material is disposed on the inside or outside surface of the enclosure or dispersed within the material forming the enclosure or a combination thereof; and a conversion circuit for supplying electric power to the light engine. a light engine for generating light of one of a plurality of wavelengths, the light engine including: a platform, at least one LED disposed on the platform; an enclosure surrounding a light generating area of the light engine, wherein the enclosure is a bulb-shaped enclosure; a base; a heat dissipating slug including a plurality of radial fins disposed about an outer periphery of the heat dissipating slug, said heat dissipating slug being in thermal communication with said light engine and located on a side of the platform opposite said at least one LED, said heat dissipating slug being inserted into said base; said base and heat dissipating slug being in thermal communication for conducting thermal energy away from the light engine, said heat dissipating slug further transferring heat from the light engine into air; a wavelength converting material to receive light generated by the light engine and convert at least a portion of the received light into visible light, said wavelength converting material is disposed on the inside or outside surface of the enclosure or dispersed within the material forming the enclosure or a combination thereof; and a conversion circuit for supplying electric power to the light engine. a platform, at least one LED disposed on the platform; an enclosure surrounding a light generating area of the light engine, wherein the enclosure is a bulb-shaped enclosure; a base; a heat dissipating slug including a plurality of radial fins disposed about an outer periphery of the heat dissipating slug, said heat dissipating slug being in thermal communication with said light engine and located on a side of the platform opposite said at least one LED, said heat dissipating slug being inserted into said base; said base and heat dissipating slug being in thermal communication for conducting thermal energy away from the light engine, said heat dissipating slug further transferring heat from the light engine into air; a wavelength converting material to receive light generated by the light engine and convert at least a portion of the received light into visible light, said wavelength converting material is disposed on the inside or outside surface of the enclosure or dispersed within the material forming the enclosure or a combination thereof; and a conversion circuit for supplying electric power to the light engine.