Here, using RNA interference screening with small interfering RNAs (siRNAs) against a number of porcine membrane protein genes, we identified the laminin receptor (LamR) to be another attachment receptor. To date, only heparan sulfate (HS) has been identified to be an attachment receptor for CSFV. IMPORTANCE Classical swine fever virus (CSFV) is the causative agent of classical swine fever (CSF), an economically important viral disease affecting the pig industry in many countries. These results indicate that LamR is a cellular attachment receptor for CSFV. We also demonstrate that LamR acts as an alternative attachment receptor, especially in SK6 cells. Moreover, an attachment assay demonstrated that LamR functions during virus attachment. Transduction of PK-15 cells with a recombinant lentivirus expressing LamR yielded higher viral titers. In inhibition assays, anti-LamR antibodies, soluble laminin, or LamR protein significantly inhibited CSFV infection in a dose-dependent manner. Confocal analysis showed that LamR is colocalized with CSFV virions on the membrane, and a coimmunoprecipitation assay indicated that LamR interacts with the CSFV E rns protein. This approach resulted in the identification of several proteins, and of these, the laminin receptor (LamR) has been demonstrated to be a cellular receptor for several viruses. In this study, we used a set of small interfering RNAs (siRNAs) against a number of porcine cell membrane protein genes to screen cellular proteins involved in CSFV infection. Hence, there must be another receptor(s) that has been unidentified to date. HS is also present on the surface of various cells that are nonpermissive to CSFV. To date, only one cellular receptor, heparan sulfate (HS), has been identified as being involved in CSFV attachment. The E rns and E2 envelope glycoproteins are responsible for the binding to and entry into the host cell by CSFV. Classical swine fever virus (CSFV) is the causative agent of classical swine fever (CSF), a highly contagious, economically important viral disease in many countries.