This study reports on crawling variability and differences in variability between infants with typical development (TD) and those with developmental delays. This longitudinal study included 0-year-old infants with no apparent dysfunction. The crawling movement in the video was coded objectively with reference to previous research. The infants were screened after 2 years of age, and the TD and suspected developmental delay (SDD) crawling codes were analysed and compared. Among TD infants, variation in hands-and-knees crawling decreased more in the group with belly-crawling experience than in the group without. However, this tendency was not observed in infants with SDD. Furthermore, TD infants showed more variable patterns of limb movement timing during belly-crawling than those with SDD. This study suggests variability during the entire crawling period. Moreover, exploration of an efficient diagonal gait was critical for crawling variability and subsequent development, which tends to be deficient in infants at risk of developmental delay.