Inorganic extended lattice structures can be incorporated into Langmuir—Blodgett (LB) films. The inorganic component not only adds lattice energy to the films, but also provides an opportunity to introduce electronic or magnetic ordering phenomena to the LB assemblies. In this Comment, LB films are described that are based on known divalent and tetravalent metal phosphonate inorganic layered solids. The LB film structures and properties are compared to the known solid-state metal phosphonates after which they are modeled. One of the films, manganese octadecylphosphonate, undergoes a magnetic ordering transition to a “weak ferromagnetic” state. It is the first example of a magnetic LB film, demonstrating how the extended lattice structure can be used to introduce new physical properties into LB films. Once the inorganic extended lattice structure is included, the possibility now exists for developing mixed organic/inorganic dual network LB films, where both the organic and inorganic networks add function.