Although a fundamental physical parameter, surface tension is difficult to measure. Common tensiometry inaccur- acy comes from failure to control air—liquid—solid contact conditions, or account for liquid meniscus geometry and buoyancy corrections. This paper describes an in situ ten- siometry technique, based on withdrawal of a thin-walled tube from the liquid interface, that enforces a known air—liquid—solid contact condition. This technique can be pursued at any level of experimental hygiene. Experimental results for filtered tap water, an alcohol—water solution, and a surfactant—water solution show that results repeatable to three significant digits are obtained with modest effort for a variety of geometrical parameters.