Studies of bilingual proficiency have largely focused on word and sentence processing, whereas the text level has received relatively little attention. We examined on-line second language (L2) text comprehension in relation to L2 proficiency with ERPs recorded on critical words separated across a sentence boundary from their co-referential antecedents. The integration processes on the critical words were designed to reflect different levels of text representation: word-form, word-meaning, and situational level (Kintsch, 1998). Across proficiency level, bilinguals showed biphasic N400/late positive component (LPC) effects related to word meaning integration (N400) and mental model updating (LPC) processes. More proficient bilinguals, compared with less proficient bilinguals, showed reduced amplitudes in both N400 and LPC when the integration depended on semantic and conceptual meanings. When the integration was based on word repetitions and inferences, both groups showed reduced N400 negativity while elevated LPC positivity. These effects reflect how memory mechanisms (processes and resources) support the tight coupling among word meaning, readers’ memory of the text meaning and the referentially-specified meaning of the text. They further demonstrate the importance of L2 semantic and conceptual processing in modulating the L2 proficiency effect on L2 text integration processes. These results align with the assumption that word meaning processes are causal components in variations of comprehension ability for both monolinguals and bilinguals.