The　Alcohol,　Smoking　and　Substance　Involvement　Screening　Test　(ASSIST)　is　an　instrument　to　screen　substance　-use-related　health　risks.　However,　little　is　known　whether　the　ASSIST　could　be　further　shortened　while　remaining　psychometrically　sound　across　different　countries,　languages,　gender　identities,　and　sexual-orientation-based　groups.　The　study　aimed　to　validate　a　shortened　11-item　ASSIST　(ASSIST-11).　Using　the　International　Sex　Sur-vey　data,　82,243　participants　(M　age　=　32.39　years)　across　42　countries　and　26　languages　completed　questions　from　the　ASSIST-11　regarding　gender　identity,　sexual　orientation,　and　other　information.　Confirmatory　factor　analysis　(CFA)　and　multigroup　CFA　(MGCFA)　evaluated　the　ASSIST-11＇s　structure　and　tested　measurement　invariance　across　groups.　Cronbach＇s　&　alpha;　and　McDonald＇s　&　omega;　were　used　to　examine　the　internal　consistency.　Cohen＇s　d　and　independent　t-tests　were　used　to　examine　known-group　validity.　The　ASSIST-11　was　unidimen-sional　across　countries,　languages,　age　groups,　gender　identities　(i.e.,　men,　women,　and　gender-diverse　in-dividuals),　and　sexual　orientations　(i.e.,　heterosexual　and　sexual　minority　individuals).　Cronbach＇s　&　alpha;　was　0.63　and　McDonald＇s　&　omega;　was　0.68　for　the　ASSIST-11.　Known-group　validity　was　supported　by　Cohen＇s　d　(range　be-tween　0.23　and　0.40)　with　significant　differences　(p-values＜0.001).　The　ASSIST-11　is　a　modified　instrument　with　a　unidimensional　factor　structure　across　different　languages,　age　groups,　countries,　gender　identities,　and　sexual　orientations.　The　low　internal　consistency　of　the　ASSIST-11　might　be　acceptable　as　it　assesses　a　broad　concept　(i.　e.,　use　of　several　different　substances).　Healthcare　providers　and　researchers　may　use　the　ASSIST-11　to　quickly　assess　substance-use　information　from　general　populations　and　evaluate　the　need　to　follow　up　with　more　detailed　questions　about　substance　use.