||Directionality in sound change, the phenomenon that a segment can change into a certain other segment but not vice versa, has generally been assumed, but has not been studied systematically. Previous studies are mainly concerned with a general discussion on the role of phonology in sound change, often attributing directionality in sound change to phonetic bias. On the basis of a sample of 5,769 historical sound changes, the current study shows that directionality in sound change is not a prominent phenomenon in absolute terms. In general, lenition is more frequent than fortition. There are two main findings. Firstly, laterals are likely to change into approximants, but not vice versa. Secondly, an asymmetry was found for segments changing into /h/ or /ʔ/. Adopting the framework of Element Theory, a phonological analysis was presented to account for those directionality patterns. Firstly, vowel elements do not add |L|. Secondly, |H| and |ʔ| do not add vowel elements. Phonological theory therefore can contribute to explaining patterns in sound change.