This article serves as an introduction to this second special issue of System on "Beliefs about Second Language Acquisition (SLA)" held by learners and/or teachers of foreign languages in a variety of contexts all over the world, and it compares and contrasts the empirical studies included in the issue. In sharp contrast to the first special System issue on beliefs about SLA, most of the studies reported in this issue draw on sociocultural theory, make use of more than one type of data, and can be characterized as qualitative in nature. In addition, the studies tend to view beliefs as variable and fixed, and focus on changes in these and/or on the interaction between beliefs and learner or teacher actions, acknowledging their relationship to be a complex one. (Contains 1 table.)