De Zonnewijzerkring is a Dutch association for anyone interested in sundials and related instruments. It promotes the study and sharing of knowledge about how sundials work and how they are designed, covering the history, mathematics, astronomy, and cultural traditions of timekeeping. Its interests also include astrolabes and nocturnals.

The association publishes books on sundial science and the quarterly magazine Zon & Tijd, available in print or as a digital edition. It organizes three annual gatherings featuring talks and opportunities for members to share projects, questions, and discoveries, as well as a summer excursion to notable sundials or collections. Members can also take a free introductory course in sundial science.

The Zonnewijzerkring offers expert advice on restoring historic sundials and designing or building new ones, with attention to construction, materials, durability, and appearance. It also documents remarkable sundials in the Netherlands and Flanders, supporting their preservation and informing future projects. Through its publications, educational activities, advice, and international contacts, the association helps keep sundial knowledge active and accessible.