We report the design and calibration of a miniature Langmuir trough that can be mounted on a microscope stage. The fully sealed trough can be used for carrying out routine monolayer experiments, such as the control and measurement of area and surface pressure, on the order of 13 h without infiltration of contaminants. In experiments carried out with the minitrough to observe the slow growing and shrinking of monolayer domains via the Ostwald ripening process, qualitative observations and quantitative results were in good agreement with theoretical expectations. The minitrough can also be used to study biological amphiphiles (e.g., lipid-protein interactions) in controlled vapor and under contaminant-free conditions.