In　order　to　investigate　the　behavior　of　partially-restrained　steel　frame　with　RC　infill　wall　(PSRCW),　two　specimens　with　one-third　scale,　one-bay,　and　two-story　were　performed　under　reversed　cyclic　lateral　load,　where　one　specimen　was　with　concealed　vertical　slits　in　the　infill　walls　and　another　specimen　with　solid　infill　walls.　Test　results　showed　that　both　specimens　obtained　enough　lateral　stiffness　for　controlling　drift　and　yielded　enough　strength　appropriate　for　resisting　lateral　load.　PSRCW　with　solid　infill　walls　exhibited　moderate　ductility　capacity　and　energy　dissipation　due　to　the　degradation　of　post-peak　strength.　PSRCW　with　concealed　vertical　slits　exhibited　much　larger　ductility,　deformability,　and　energy　dissipation　capacity　than　the　other　one.　Once　concealed　vertical　slits　were　crushed,　infill　walls　behaved　as　a　series　of　flexural　columns　provided　fairly　ductile　response　and　stable　cyclic　performance.　PSRCW　with　concealed　vertical　slits　can　improve　post-peak　strength　degradation　considerably.　In　addition,　damaged　PSRCW　structure　subjected　to　earthquake　is　easy　to　be　repaired,　through　knocking　off　the　heavy　crushed　infill　walls　and　recasting　concrete　infill　walls.　This　is　another　advantage　of　this　composite　structure.　(C)　2011　Elsevier　Ltd.　All　rights　reserved.