This paper puts forward the case that one of the factors constraining principled learningoriented assessment practices is lack of trust. It examines a number of assessment dimensions in which trust or distrust plays a role. These issues are illustrated via a discussion of two different iterations of the same module taught in a teacher education institution. Through this example, the author analyses how accountability forces and distrust created an atmosphere which constrained the use of innovative assessment methods. The paper discusses how trust might be developed, some of the barriers arising, and the relationship between trust and good assessment practices. It concludes by sketching some possible avenues for further research into stakeholders' perceptions of the interplay between trust and assessment.