BACKGROUND:While research in high-income countries (HICs) has established high costs associated with alcohol's harm to others (AHTO) in the workplace, scant attention has been paid to AHTO in the workplace in lower- or middle-income countries (LMICs). AIM:To compare estimates and predictors of alcohol's impacts upon coworkers among workers in 12 countries. METHODS:Cross-sectional surveys from 9,693 men and 8,606 women employed in Switzerland, Australia, the United States, Ireland, New Zealand, Chile, Nigeria, Lao PDR, Thailand, Vietnam, India, and Sri Lanka. Five questions were asked about harms in the past year because of coworkers' drinking: Had they (i) covered for another worker; (ii) worked extra hours; (iii) been involved in an accident or close call; or had their (iv) own productivity been reduced; or (v) ability to do their job been affected? Logistic regression and meta-analyses were estimated with 1 or more harms (vs. none) as the dependent variable, adjusting for age, sex, rurality of location, and the respondent worker's own drinking. RESULTS:Between 1% (New Zealand) and 16% (Thailand) of workers reported that they had been adversely affected by a coworker's drinking in the previous year (with most countries in the 6 to 13% range). Smaller percentages (<1% to 12%) reported being in an accident or close call due to others' drinking. Employed men were more likely to report harm from coworkers' drinking than employed women in all countries apart from the United States, New Zealand, and Vietnam, and own drinking pattern was associated with increased harm in 5 countries. Harms were distributed fairly equally across age and geographic regions. Harm from coworkers' drinking was less prevalent among men in HICs compared with LMICs. CONCLUSIONS:Workforce impairment because of drinking extends beyond the drinker in a range of countries and impacts productivity and economic development, particularly affecting men in LMICs.