This article reports on an experiment investigating the effects of featural Relativized Minimality (Friedmann et al., 2009) on the representation and processing of relative clauses in the second language (L2) English of Mandarin speakers. Object relatives (ORCs) are known to cause greater problems in first language (L1) acquisition and in adult processing than subject relatives (SRCs). Featural Relativized Minimality explains this in terms of intervention effects, caused by a DP (the subject of the ORC) located between the relative head and its source. Intervention effects are claimed to be reduced if the relative head and the intervenor differ in features, such as number (e.g. I know the king who the boys pushed). We hypothesize that L2 learners will show intervention effects when processing ORCs and that such effects will be reduced if the intervenor differs in number from the relative head. There were two tasks: picture identification and self-paced reading. Both manipulated relative clause type (SRC/ORC) and intervenor type (±plural). Accuracy was high in interpreting relative clauses, suggesting no representational problem. Regarding reading times, ORCs were processed slower than SRCs, supporting an intervention effect. However, faster reading times were found in ORCs when intervenor and head noun matched in number, contrary to hypothesis. We suggest that our more stringent stimuli may have resulted in the lack of an effect for mismatched ORCs, in contrast to some earlier findings for L1 acquirers.