Eukaryotic cells respond to heat stress by activating the transcription factor HSF1. In addition to its role in stress response, HSF1 also functions in protein homeostasis, aging, innate immunity, and cancer. Despite prominent HSF1 involvement in processes pertinent to human health and disease, there are still gaps in our understanding of HSF1. For example, controversy exists regarding the localization of HSF1, the identity of HSF1 regulators, and the function and conservation of heat-induced HSF1 stress granules. Many of the physiological roles for HSF1 have been defined using the model organism Caenorhabditis elegans, yet little is known about how the molecular and biological properties of HSF-1 in C. elegans compare to HSF1 in other organisms, including humans. To address these questions, we generated animals expressing physiological levels of a GFP-tagged C. elegans HSF-1 protein. We studied the localization of HSF-1