Attachment anxiety is characterized by rumination about romantic relationships, particularly when the attachment system is activated. Two studies investigated the hypothesis that more anxiously attached individuals would experience cognitive load when attachment concerns were activated (vs. not activated). Study 1 found that more anxious persons encountering relationship threat (vs. no threat) demonstrated greater holistic processing on a shape categorization task, a type of processing reflective of cognitive load. Study 2 found that more anxious persons encountering relationship threat (vs. no threat or academic threat) exhibited slower reaction times on a Stroop task, a pattern also reflective of cognitive load. This research lends novel insight into how attachment system activation and relationship reflection pose a cognitive vulnerability for more anxious individuals.