This study investigates the acquisition of the English vowels [æ] and [ʌ] by Colombian learners of American English. Thirty speakers of Colombian Spanish residing in the United States participated in this study. A multiple-choice identification task demonstrated that participants were proficient at identifying [æ] and [ʌ], though the accuracy rate was somewhat lower than for a number of other English vowels used for comparison. When misidentified, [æ] and [ʌ] were most frequently confused with each other or with the low back vowel [ɑ]. In a production task completed by both bilingual Spanish speakers and monolingual English speakers, learners’ [æ] and [ʌ] were distinct from native monolingual English productions. The nature of the acoustic differences between native speakers’ vowels and learners’ vowels suggested that Colombian speakers’ English renditions of [æ] and [ʌ] were affected by their Spanish [a]. Further analysis revealed that learners’ [æ] was not statistically different from their own production of Spanish [a]. These results are compatible with the assumption emerging from previous research that speakers of Spanish acquiring English assimilate, to a varying degree, English low and low-mid vowels to Spanish [a]—a single vowel found in this area of the vowel space in Spanish.