This study investigates whether L2 learners employ similar processing strategies as native speakers when disambiguating attachment of a relative clause (RC) in Korean as a second language (KSL). Different processing strategies were tested with temporarily ambiguous sentences containing RCs when the head NP is a complex NP (NP1 of NP2), in which either NP1 (low attachment, LA) or NP2 (high attachment, HA) can be an antecedent. The RCs were controlled for length (short vs. long) and position-sentence initial (scrambled word order) vs. sentence medial (canonical word order). Native speakers consistently showed a clear HA preference regardless of the length or the position of the RCs, whereas KSL learners showed a clear LA preference. The attachment differences between L1 and L2 are discussed in terms of transfer and prosodic sensitivity.