Mental imagery often occurs during testimonial belief transmission: a testifier often episodically remembers or imagines a scene while describing it, while a listener often imagines that scene as it’s described to her. I argue that getting clear on imagery’s psychological roles in testimonial belief transmission has implications for some fundamental issues in the epistemology of testimony. I first appeal to imagery cases to argue against a widespread ‘internalist’ approach to the epistemology of testimony. I then appeal to the same sort of case to argue for an alternative, externalist view.