Bed-sharing is a controversial but common parenting practice with claimed benefits for emotional and behavioral development. Using data from the UK Millennium Cohort Study ( N = 16,599), this prospective study investigated whether bed-sharing at 9 months is associated with childhood internalizing and externalizing symptom trajectories. Children were grouped by their patterns of co-developing internalizing and externalizing symptoms from 3 to 11 years of age using a parallel process latent class growth analysis. There were no associations between bed-sharing at 9 months of age and internalizing and externalizing symptom trajectories across childhood. This finding suggests that bed-sharing at 9 months has no positive or negative influence on the development of internalizing and externalizing symptoms across childhood. Clinicians should inform parents that bed-sharing during the second half of the first year is unlikely to have an impact on the later emotional and behavioral development of the children.