An aqueous herbicidal concentrate solution comprising: (a) glyphosate or a salt or ester thereof in a concentration greater than 420 grams acid equivalent per liter; (b) an amidoalkylamine surfactant of structure: wherein R 1 is alkyl having an average of from 4 carbon atoms to 18 carbon atoms, R 2 and R 3 are independently alkyl having from 1 to 4 carbon atoms, and R 4 is alkylene having from 1 to 4 carbon atoms; and (c) at least one co-surfactant comprising an alkoxylated tertiary amine, an alkoxylated quaternary amine, an alkoxylated tertiary etheramine, an alkoxylated quaternary etheramine, an alkoxylated etheramine oxide, an alkoxylated tertiary amine oxide, an alkoxylated alcohol, a phosphate ester of alkoxylated tertiary amine, a phosphate ester of alkoxylated etheramine, a phosphate ester of alkoxylated alcohol, or a combination thereof; wherein the alkoxylated tertiary amine surfactant is of structure: wherein R 1 is hydrocarbyl or substituted hydrocarbyl having from 4 to 22 carbon atoms, R 2 and R 3 are each independently hydrocarbylene having 2, 3, or 4 carbon atoms, and the sum of x and y is an average value ranging from 2 to 50; wherein the alkoxylated quaternary amine surfactant is of structure: wherein R 1 is hydrocarbyl or substituted hydrocarbyl having from 4 to 22 carbon atoms, R 2 and R 3 are each independently hydrocarbylene having 2, 3, or 4 carbon atoms, R 4 is hydrocarbyl or substituted hydrocarbyl having from 1 to 4 carbon atoms, the sum of x and y is an average value ranging from 2 to 50, and X is a charge balancing counter-anion; wherein the alkoxylated tertiary etheramine surfactant is of structure: wherein R 1 is hydrocarbyl or substituted hydrocarbyl having from 4 to 22 carbon atoms; R 2, R 3 and R 4 are each independently hydrocarbylene having 2, 3, or 4 carbon atoms; m is an average number from 1 to 10; and the sum of x and y is an average value ranging from 2 to 60; wherein the alkoxylated quaternary etheramine surfactant is of structure: wherein R 1 is hydrocarbyl or substituted hydrocarbyl having from 4 to 22 carbon atoms; R 2, R 3 and R 4 are each independently a hydrocarbylene having 2, 3, or 4 carbon atoms; m is an average number from 1 to 10; the sum of x and y is an average value ranging from 2 to 60; R 5 is hydrocarbyl or substituted hydrocarbyl having from 1 to 4 carbon atoms; and A is a charge balancing counter-anion; wherein the alkoxylated etheramine oxide surfactant is of structure: wherein R 1 is hydrocarbyl or substituted hydrocarbyl having from 4 to 22 carbon atoms; R 2, R 3 and R 4 are each independently hydrocarbylene having 2, 3, or 4 carbon atoms; m is an average number from 1 to 10; and the sum of x and y is an average value ranging from 2 to 60; wherein the alkoxylated tertiary amine oxide surfactant is of structure: wherein R 1 is hydrocarbyl or substituted hydrocarbyl having from 4 to 22 carbon atoms; R 2 and R 3 are each independently hydrocarbylene having 2, 3, or 4 carbon atoms; and the sum of x and y is an average value ranging from 2 to 50; wherein the alkoxylated alcohol surfactant is of structure (VIII): R 1 -O-(R 2 O) n H Structure (VIII) wherein R 1 is hydrocarbyl or substituted hydrocarbyl having from 4 to 22 carbon atoms; R 2 is hydrocarbylene having 2, 3, or 4 carbon atoms; n is an average value ranging from 2 to 50; wherein the phosphate ester of the alkoxylated tertiary amine surfactant is of structure (IXa) or structure (IXb): wherein each R 1 is independently hydrocarbyl or substituted hydrocarbyl having from 4 to 22 carbon atoms, R 2 and R 3 are each independently hydrocarbylene having 2, 3, or 4 carbon atoms, the sum of each x and y group is independently an average value ranging from 2 to 60, and R 4 and R 5 are each independently hydrogen, hydrocarbyl or substituted hydrocarbyl having from 1 to 6 carbon atoms; wherein the phosphate ester of alkoxylated etheramine surfactant is of structure (Xa) or structure (Xb): wherein each R 1 is independently hydrocarbyl or substituted hydrocarbyl having from 4 to 22 carbon atoms; each R 2, R 3 and R 4 are each independently hydrocarbylene having 2, 3, or 4 carbon atoms; each m is independently an average number from 1 to 10; the sum of each x and y group is independently an average value ranging from 2 to 60; and R 5 and R 6 are each independently hydrogen, hydrocarbyl or substituted hydrocarbyl having from 1 to 6 carbon atoms; and wherein the phosphate ester of alkoxylated alcohol surfactant is of structure (XIa) or (XIb): wherein each R 1 is independently hydrocarbyl or substituted hydrocarbyl having from 4 to 22 carbon atoms; each R 2 is independently hydrocarbylene having 2, 3, or 4 carbon atoms; each m is independently an average number from 1 to 60; and R 3 and R 4 are each independently hydrogen, hydrocarbyl or substituted hydrocarbyl having from 1 to 6 carbon atoms. (a) glyphosate or a salt or ester thereof in a concentration greater than 420 grams acid equivalent per liter; (b) an amidoalkylamine surfactant of structure: wherein R 1 is alkyl having an average of from 4 carbon atoms to 18 carbon atoms, R 2 and R 3 are independently alkyl having from 1 to 4 carbon atoms, and R 4 is alkylene having from 1 to 4 carbon atoms; and (c) at least one co-surfactant comprising an alkoxylated tertiary amine, an alkoxylated quaternary amine, an alkoxylated tertiary etheramine, an alkoxylated quaternary etheramine, an alkoxylated etheramine oxide, an alkoxylated tertiary amine oxide, an alkoxylated alcohol, a phosphate ester of alkoxylated tertiary amine, a phosphate ester of alkoxylated etheramine, a phosphate ester of alkoxylated alcohol, or a combination thereof;