A vertical soil extensometer was developed to measure differential soil movement between two reference points. The extensometer incorporates telescoping casing sections installed in a bore hole with the aid of a section spacing device. The length of the casing can thus expand and contract with the soil. Connecting pipes inside the casing transfer upper and lower anchor movements to an electrical sensor, without interference from the soil around the casing. The extensometer is easily fabricated from standard materials and purchased components. This paper is intended to provide enough details to enable the reader to construct the device. Installation procedures are also presented.