Introduction: Recent PEDIG studies have described a spectrum of early-onset esotropia (ET), from small variable angle to “classical” large heterotropias. We report here a similar spectrum of early-onset ET in infant monkeys, with emphasis on the relationship between visuomotor deficits, central nervous system circuitry, and orbital anatomy. Methods: Eye movements were recorded in macaque monkeys with natural (n = 3) and optically induced (n = 7) ET to assess alignment, disparity-vergence, latent nystagmus, DVD, and pursuit/OKN asymmetries. Acuity was measured by SSVEP and stereopsis thresholds established using random-dot stimuli. Geniculo-striate pathways were then analyzed with neuroanatomic tracers and metabolic labels. EOMs were examined by high-resolution magnetic resonance imaging and anatomic sectioning of whole orbits. Results: ET ranged from 4° to 25° (7–44Δ) with fixation preference (if any) varying idiosyncratically (as in human). Severity of ocular motor dysfunction (ie, vergence insensitivity, nystagmus velocity, DVD amplitude, nasotemporal gain asymmetry), and severity of stereopsis deficit related to ET angle and duration (regression analysis; p = 0.036). Animals with marked behavioral deficits tended to have marked V1 neuroanatomic deficits, evident as fewer binocular horizontal connections and denser metabolic suppression. Orbital MRI/anatomic analysis showed no EOM/pulley or cranial nerve end-plate anomalies compared with (n = 3) controls. Conclusions: The ET spectrum in nonhuman primates is remarkably similar to that reported in human infants. Concomitant ET in these primates cannot be ascribed to abnormalities of the extraocular muscles or orbit. These findings, combined with epidemiologic studies of human, indicate that perturbations of CNS binocular pathways in early development are the primary cause of the infantile ET syndrome.