Introduction Little is known about the degree to which U.S. Army soldiers in the Reserve Components (Army National Guard and Army Reserve) and Active Component (Regular Army) differ with respect suicide attempt (SA) risk during high-stress times, such as deployment. Method Using administrative person-month records of enlisted soldiers on active duty during 2004–2009, we identified 1170 soldiers with a medically documented SA during deployment and an equal-probability control sample of other deployed soldiers (n = 52,828 person-months). Logistic regression analyses examined the association of Army component (Guard/Reserve vs. Regular) with SA before and after adjusting for socio-demographic and service-related predictors. Results Guard/Reserve comprised 32.1% of enlisted soldiers and 19.7% of suicide attempters in-theater, with a SA rate of 81/100,000 person-years (vs. 157/100,000 person-years among Regular; rate ratio = 0.5 [95% CI = 0.5–0.6]). Risk peaked near mid-deployment for both groups but was consistently lower for Guard/Reserve throughout deployment. Guard/Reserve had lower odds of SA after adjusting for covariates (OR = 0.7 [95%CI = 0.6–0.8]). Predictors of SA were similar between components. Conclusions Guard/Reserve and Regular soldiers had similar patterns and predictors of SA during deployment, but Guard/Reserve had lower risk even after controlling for important risk factors. Additional research is needed to understand the lower SA risk among Guard/Reserve in-theater.