The research presents test and finite element analysis results of steel wide flange column-to-beam connections using internal flange stiffeners (IFS). Four full-scale moment connections were tested. All specimens had bolted web connection and welded beam-to-column flange using complete joint penetration welds. One specimen without internal flange stiffeners was tested as a benchmark. Three rehabilitated moment connections had different shape stiffeners and beam material. All rehabilitated moment connections showed excellent performance under the AISC (2005) seismic loads in excess of 4% drift. All specimens were also modeled using the computer program ABAQUS (2003) for the correlation study.