In a paired-associate learning (PAL) task, Dutch university students (n = 129) learned 20 English second language (L2) idioms either receptively or productively (i.e., L2-first language [L1] or L1-L2) and were tested in two directions (i.e., recognition or production) immediately after learning and 3 weeks later. Receptive and productive performance was affected by direction of learning. This finding parallels findings from PAL experiments on L2 individual-word learning. On a productive test, productive learners had a sizable advantage over receptive learners, whereas on recognition, receptive learners outperformed productive learners. Two idiom characteristics, imageability (capacity to evoke a mental image) and transparency (overlap between literal and figurative meaning), as assessed in a norming study by an independent sample (n = 80), qualified these findings. Indicating the importance of dual coding in idiom learning, imageability predicted performance, and receptive learning was particularly inefficient for low imageable idioms. Transparency was a weaker predictor of performance and only affected recognition.