We report outcomes from a multi-year study of writing center-sponsored writing groups at a land-grant university in the American Midwest to advocate for the unique needs of international STEM graduate students. Survey participants self-reported writing confidence, academic knowledge, amenability to peer feedback and collaboration, and other characteristics. Scores were low for international students, lower for STEM students, and lowest among international STEM students. International STEM graduate students also reported the highest degrees of improvement between pre- and post-participation surveys. We argue that writing centers and academic departments need to develop support services tailored to the unique needs of this population.