The production of more economic and durable concrete slabs by using glass fibre-reinforced plastic ( GFRP ) as a corrosion-resistant reinforcement, combined with compressive lateral loading - compressive membrane action ( CMA ), was investigated. It was considered that the loadbearing capacity may be increased by the arching of the slabs created by the compressive forces. Concrete slabs reinforced by steel or GFRP, some simply supported and others fitted with a steel frame to provide lateral restraint, were loaded to failure. The simply supported, GFRP-reinforced slabs exhibited greater deflection than the equivalent steel-reinforced slab. The use of a lateral restraint reduced the deflection of the GFRP-reinforced slabs more than that of the steel-reinforced equivalents. The laterally restrained GFRP-reinforced slabs exhibited slightly higher loadbearing capacity. It was concluded that the ultimate strength of laterally-restrained slabs depended more on the concrete compressive strength than on the reinforcement, and that GFRP was a viable reinforcement. 11 refs.