This paper covers six interrelated issues in formative assessment (aka, ‘assessment for learning’). The issues concern the definition of formative assessment, the claims commonly made for its effectiveness, the limited attention given to domain considerations in its conceptualisation, the under‐representation of measurement principles in that conceptualisation, the teacher‐support demands formative assessment entails, and the impact of the larger educational system. The paper concludes that the term, ‘formative assessment’, does not yet represent a well‐defined set of artefacts or practices. Although research suggests that the general practices associated with formative assessment can facilitate learning, existing definitions admit such a wide variety of implementations that effects should be expected to vary widely from one implementation and student population to the next. In addition, the magnitude of commonly made quantitative claims for effectiveness is suspect, deriving from untraceable, flawed, dated, or unpublished sources. To realise maximum benefit from formative assessment, new development should focus on conceptualising well‐specified approaches built around process and methodology rooted within specific content domains. Those conceptualisations should incorporate fundamental measurement principles that encourage teachers and students to recognise the inferential nature of assessment. The conceptualisations should also allow for the substantial time and professional support needed if the vast majority of teachers are to become proficient users of formative assessment. Finally, for greatest benefit, formative approaches should be conceptualised as part of a comprehensive system in which all components work together to facilitate learning.