Many learners of a foreign language (L2) struggle to correctly pronounce newly learned speech sounds, yet many others achieve this with apparent ease. Here we explored how a training study of learning complex consonant clusters at the very onset of L2 acquisition can inform us about L2 learning in general and individual differences in particular. To this end, adult Dutch native speakers were trained on Slovak words with complex consonant clusters (e.g., "pstruh"/pstrux/"trout", "stvrt"/tvrc/"quarter") using auditory and orthographic input. In the same session following training, participants were tested on a battery of L2 perception and production tasks. The battery of L2 tests was repeated twice more with 1 week between sessions. In the first session, an additional battery of control tests was used to test participants' native language (L1) skills. Overall, in line with some previous research, participants showed only weak learning effects across the L2 perception tasks. However, there were considerable individual differences across all L2 tasks, which remained stable across sessions. Only two participants showed overall high L2 production performance that fell within 2 standard deviations of the mean ratings obtained for an L1 speaker. The mispronunciation detection task was the only perception task which significantly predicted production performance in the final session. We conclude by discussing several recommendations for future L2 learning studies. (Contains 2 figures, 2 tables, and 8 notes.)