To disambiguate infants' attentional bias towards fearful facial expressions, we applied a facial expression cueing paradigm to 36 6-month-old and 33 12-month-old infants, with 21 infants taking part at both ages. Infants made saccades towards a peripheral target preceded by a happy, fearful, or neutral cue directing their attention to the target location (congruent) or the wrong location (incongruent). The results show that infants were faster to respond when shown a fearful (vs. happy) face as a congruent cue, which is consistent with previous studies referring to fearful vigilance, while an incongruent fearful cue reduces attention shifts to the target on the opposite side of the monitor to a greater extent than an incongruent happy cue at 12 months, implying that a fearful facial expression prolongs attentional disengagement or is associated with a greater narrowing of attention. Additionally, the latencies of 6-month-olds were significantly faster than those of 12-month-olds in a congruent condition. The relationship between attentional bias and temperamental disposition was examined using the Infant Behavior Questionnaire-Revised. High temperamental orienting scores partly correlated with attentional bias at 12 months. The contributions of attentional brain networks to socio-cognitive and emotional development are also discussed.