This study aims to present the validation of a test designed to assess young learners' general L2 English vocabulary knowledge, the Young Learner Vocabulary Assessment Test (YLVAT). YLVAT consists of 37 items selected from the K1-2 frequency levels of the Productive and Vocabulary Levels Tests. In the study, Swedish learners (N = 52, age 12) took YLVAT and filled out an evaluation; scores from the national test of English (reading and listening comprehension) were also collected. Four validity measurements were used: the spread of YLVAT scores, correlation with the national test--reading, correlation with the national test--listening, and evaluation responses. YLVAT results point to a sufficient spread of scores (M = 18.9, SD = 6.5). There were significant correlations between YLVAT and (1) reading (r = 0.597**), (2) listening (r = 0.541**), (3) perceived test difficulty (r[subscript s] = -0.538**), and (4) how fun it was to take the test (r[subscript s] = 0.683**). An ANOVA showed that learners who found YLVAT "easy" or "very easy" scored significantly (p = 0.000) higher (26.1) than those who found it "difficult" (18.3) or "very difficult" (12.9). Finally, teachers found YLVAT to correlate with their own assessment of learners' vocabulary.