This article analyzes teacher professional development (PD) mandated by the implementation of portfolio-based language assessment (PBLA) in government-funded adult language learning programs in Canada. Through the lens of conceptualizations of teacher learning (TL), the study examined PBLA teacher-training materials, 247 teacher surveys, and participant interviews pertaining to two contrasting cases. The analysis of teacher experiences in PBLA PD revealed limited theoretical and empirical connections to recent developments in second language teacher education (SLTE). While current SLTE research emphasizes self-directed TL, the PBLA train-the-trainer model demonstrates top-down knowledge transmission with a potentially undermining evaluative component. The hierarchical transmission of knowledge created for teachers without opportunities for knowledge building by teachers contradicts current understandings of TL as a complex sociocultural activity. Limited effectiveness of PBLA as a TL experience may be further diminished by its potential use for punitive surveillance, as demonstrated in the extreme case analysis. As a result of this study, Richards and Farrell's conceptualizations of TL were complemented with an additional perspective informed by sociocultural theory--TL as dialogic interaction. The disconnect of PBLA vision and practice from current SLTE requires further research and attention from policymakers.