This meta-analysis of maternal sensitivity and infant/toddler attachment security includes 41 studies with 2243 dyads. Its purpose is to explore the impact of time between assessments of maternal sensitivity and attachment security on the strength of association between these two constructs. We also examined the interrelationships between this moderator variable and other moderators identified in the literature, such as age and risk status of the sample. We found an overall effect size of r = .27 linking sensitivity to security. However, time between assessment of sensitivity and attachment security moderates this effect size, such that: (1) effect sizes decrease dramatically as one moves from concurrent to nonconcurrent assessments, and (2) temporally distant assessments are a sufficient condition for small effect size; that is, if the time between assessments is large, then a relatively small effect size linking sensitivity and attachment is certain. We also found that time between sensitivity and attachment assessments may account for earlier findings indicating that effect sizes linking sensitivity to security differ according to age of child and sample risk status. Findings are discussed in terms of internal working models and environmental stability.