A handheld refractometer (HHR) is a versatile instrument in the chemistry lab or in the workplace. It is also inexpensive enough (<$25 U.S.) that all students in a chemistry lab can have one or students completing laboratories remotely can purchase one. We report four applications of two different HHRs: one HHR for which the scale reads directly in refractive index from 1.333 to 1.360 and one HHR for which the scale reads from 0 to 80 °Brix corresponding to refractive indices from 1.333 to 1.491. The four applications involve linear relationships between solution concentration and refractive index for sucrose solutions and coffee solutions as well as nonideal solution behavior of methanol/water solutions and 2-propanol/water solutions. The use of an HHR is ideally suited to a range of inquiry-based experiments and can be incorporated into chemistry lab courses at a variety of levels and in remote learning lab experiences. We describe four broad categories of projects involving the use of HHRs.