Studies on the role of storage and computation in native speakers' processing of complex words have shown morphological priming effects that differ between regular and irregular inflection (see Clahsen 1999, Rastle and Davis, 2008 for review): when stems of regularly inflected target words presented after morphologically related prime words (walked-WALK), word/non-word-decisions are made faster than after the presentation of unrelated primes (bank- WALK), often just as fast as after the presentation of the stem itself (walk- WALK). For irregulars like slept, priming of the stem (e.g. sleep) is reduced. Some researchers have argued that this results from regularly inflected words being decomposed into affixes and stems, which are then pre-activated for word/non-word decisions, while irregulars are stored as wholes that are only associatively linked to their stems (Clahsen 1999). Others argue that priming-effect sizes depend on formal/orthographic overlap between primes and targets (Gonnerman et al., 2007). It is also debated whether second language (L2) learners employ different processing mechanisms, or if they are just slower and less efficient (Indefrey, 2006). Moreover, it is unclear whether formal/orthographic information plays the same role in L1- and L2-processing. This thesis presents four priming experiments with English native speakers and L2- learners of English, with Arabic and Mandarin Chinese Ll. These experiments used different priming methods (cross-modal, overt visual and masked priming) to study regularly inflected verbs (walked-WALK), irregularly inflected verbs (sleep-SLEP1) and orthographic ally/formally related pairs (yellow-YELL). The results show significant morphological priming in all groups. L1-learners exhibited the expected priming reduction for irregulars and no formal/orthographic priming. L2-learners showed morphological priming, but less priming for regulars than the Ll-group and significant orthographic priming effects for purely orthographically related primes (yellow-YELL). This suggests that L2-speakers are less sensitive to the morphological regular/irregular-distinction and rely more on orthographic information compared to Ll speakers.