This study explores undergraduate college students' difficulties in translating English and Arabic plurals. Results of an English and Arabic plural translation test showed that cases where Arabic plurals match those of English in English were translated correctly. However, the students had difficulty translating the following: (i) Arabic plurals that have a singular English equivalent [Arabic characters omitted] "jewelry"; (ii) Arabic duals with two different singular stems: [Arabic characters omitted] "the Tigris and Euphrates"; (iii) multiple Arabic plurals, i.e. plurals of paucity and multiplicity: [Arabic characters omitted] "chicken", [Arabic characters omitted] "a number of hens"; (iv) stems with two plurals and different usages: "economics" [Arabic characters omitted], "economies" [Arabic characters omitted]; (v) plural compound: "image processors" [Arabic characters omitted]; (vi) English nouns ending in -ies that have the same singular and plural form: "series, species"; (vii) distinguishing singular and plural forms of the same base when it has two part of speech such as a noun and adjective as in: "rich & riches"; "wood & woods"; (viii) foreign/Latin singular and plural forms: "indices, larvae, tempi, oases"; (ix) names of tools and articles of dress consisting of two parts ending in -s: "scissors" [Arabic characters omitted], "scales" [Arabic characters omitted] and others. Error data analysis showed that students made more errors in translating Arabic than English plurals, and made more interlanguage than interlangauge errors. Their responses to the Arabic-English plural translation test reflected more morphological than semantic difficulties, but their responses to the English-Arabic plural translation test reflected more semantic problems. They tended to translate imitatively rather than discriminately and literal translation was the most common strategy. When they could not access the meaning of a noun on the test, they gave an equivalent that is phonologically close, gave a paraphrase, an explanation, or an extraneous equivalent. In translating English and Arabic plurals, transfer is bidirectional, i.e., students transfer the noun morphology from the source language to the target language whether the source language is Arabic (L1) or English (L2). Implications for plural translation instruction are given.