Lightweight Foam Concrete (LFC) has become an attractive construction material, especially for non-structural components since it has less density and better acoustic and thermal insulation properties. However, compared with normal-weight concrete, it has lower mechanical properties that can be improved by adding supplementary cementitious materials like fly ash. This research paper describes the experimental work done to develop LFC mixes with various percentages of foam and fly ash. It also investigates some of their physical, mechanical, and thermal properties. The developed LFC mixes consist of sand, cement, foam, water, and fly ash. The foam amount varies from 10 to 40% of the total mix volume with an increment of 10%. The fly ash partially replaces sand by 10, 20, and 30% of its weight. Test results show that density, compressive strength, and thermal conductivity decrease as foam amount increases. Partially replacing sand with fly ash improved the compressive strengths but increased densities and thermal conductivities. For the LFC mixes with 10 and 20% foam, the densities, compressive strengths, and thermal conductivities increased as the fly ash amount increased up an optimum value (ranging between 10 and 20% of fly ash) and then decreased at 30% fly ash. However, for the 30% foam mixes, the densities, compressive strengths, and thermal conductivities continued to increase as the fly ash content increased.