The impact of post-structuralist ideas in psychology has brought issues of relativism and multiple meanings to the fore. However, there is a tension between science and subjectivity, between formulating a general and generalizable account and attending to particularity. In this paper I explore how these issues are played out in developmental psychological research. I argue that attending to the power relations that are conferred by structural research practices and subject positions set up within discourse can not only highlight previously unacknowledged diversity of meaning, but also close off total interpretive relativism. Dominant discourses structuring developmental psychology work to occlude the indeterminacy of meaning, in the sense that developmental research practices fail to reflect ambiguities of interpretation. But on the other hand, rather than celebrating the plurality of meanings, we should be aware that acknowledging power relations disambiguates, or fixes, otherwise mutually co-existent interpretations. In terms of developing a critical theory of research practice and analysis, this permits discussion of notions of discursive position and strategy without lapsing either into voluntarism or mechanism.