Abstract: Apparatus and processes for liquefying process gases using multi-stage active magnetic regenerative refrigerators are disclosed. The apparatus and processes can be configured to liquefy process streams that liquefy below ˜200 K, such as ethane, methane, argon, nitrogen, neon, hydrogen and/or helium process gases. Active magnetic regenerative liquefiers use multiple successive active magnetic regenerator stages, with each stage using a compositionally distinct magnetic refrigerant material having a distinct Curie temperature. In some aspects, the refrigerant material in each successive stage has a Curie temperature of about 20 K-40K different from that of neighboring stages. Heat transfer fluid flows are directed to improve system efficiency.