This paper deals with the seismic behavior of an inverted-V-braced structure with braces of intermediate slenderness (\IL\N/\Ir\N=70–120). These are often designed as earthquake-resistant elements of low- and middle-rise buildings. The post-buckling behavior of the brace and the interaction between the brace and the braced bay beam mainly affect the total seismic behavior of the frame. These effects are discussed by using the experimental results on the half-scaled three-story models of the inverted-V-braced system which were carried out at the Building Research Institute, the Ministry of Construction, Japanese Government, as part of the U.S.-Japan Cooperative Earthquake Research Program Utilizing Large-Scale Testing Facilities. Based on these findings, a simple but reasonable hysteresis model for the inverted-V-braced systems is proposed to predict the hysteretic lateral shear force versus inter-story drift relation of the structural system.