Abstract: Background: Suicidal thoughts and behaviors are an acute public health issue, particularly among US Veterans. The interpersonal-psychological theory of suicide posits that unmet interpersonal needs, specifically thwarted belongingness (TB) and perceived burdensomeness (PB) contribute to desire for death by suicide and increased suicidal ideation (SI). However, little is known about the neurochemical correlates of TB and PB. Prior research using proton magnetic resonance spectroscopy (1H-MRS) has implicated glutamate (Glu) and glutamine (Gln), as well as gamma-aminobutyric acid (GABA), in SI and related psychiatric disorders. The current study sought to examine the relationship between thwarted belongingness and perceived burdensomeness and concentrations of Gln, Glu, and GABA in US Veterans with and without a history of SI. Methods: In this preliminary exploratory study, 25 US Veterans underwent a two-dimensional J-resolved 1H-MRS exam to measure in vivo concentrations of Gln, Glu, and GABA in the anterior cingulate cortex. Veterans also completed the Columbia Suicide Severity Rating Scale to characterize lifetime history of suicidal thoughts and behaviors and the Interpersonal Needs Questionnaire to measure TB and PB. Results: Reduced Gln/water was associated with increased TB and PB scores. Reduced Gln/Glu was associated with increased TB scores. Veterans with a lifetime history of SI also exhibited reduced Gln/water and Gln/Glu. Follow-up regression models showed that neither TB, PB, nor SI history were uniquely associated with Gln, but TB was uniquely associated with Gln/Glu. Conclusion: Results provide preliminary evidence that TB and PB may be linked to abnormalities in Gln. This work further integrates biological and psychosocial perspectives on SI.