United by a focus on the early modern Atlantic, these papers explore methodological questions about nonhumans, agency, material culture, labor, and race that speak to many historical periods and geographic sites. A number of these papers integrate New Materialist scholarship by tracing physical interactions between people and other animals. We also draw from modern-day scientific studies to illuminate these encounters and consider the challenges of doing so. Christopher Blakley uncovers how British naturalists in the West Indies relied on enslaved African collectors to accumulate specimens of marine animals, and how collecting animals increased their scientific credit and functioned as a form of leisure. Whitney Barlow Robles examines the creation and circulation of flattened fish specimens pressed on paper—a technique that relied on various forms of lay and enslaved labor—and reconstructs this historical preservation method using a fish from the grocery store to consider natural history’s material practices and interpersonal interactions of particular people and animals. Charlotte Carrington-Farmer connects New England’s horse trade to the wider currents of the Atlantic economy, notably the market for sugar and slaves, and also considers how horses and slaves labored together on sugar plantations. Finally, Iris Montero Sobrevilla examines why the Mexica—or Aztecs—chose a hummingbird as their main deity through offering a reading of the Florentine Codex that emphasizes both the empirical vein of the naturalist tradition of the Mexica and the preeminence of visual thinking for conveying findings about nature.