<p>The reactivity of amorphous aluminosilicate precursors constitutes a primary determinant of performance in alkali-activated materials (AAMs). This review critically examines the structure–reactivity relationships governing dissolution behaviour and gel formation, focusing on the influence of atomic- and mesoscale structural features. Key parameters, including network polymerisation, aluminium coordination, and the distribution of network-modifying cations, are evaluated with respect to their effects on alkaline dissolution kinetics and the nature of the resulting binding phases. The limitations of conventional bulk composition-based descriptors are addressed, particularly in heterogeneous industrial precursors where structural variability substantially modulates reactivity. Current methodologies for quantifying precursor reactivity are assessed, with emphasis on the absence of standardised protocols and the challenges inherent in isolating the chemically accessible amorphous fraction. Advances in characterisation techniques alongside the emergence of physics-based and data-driven modelling approaches are examined as complementary pathways toward improved predictive capability. The synthesis of multi-scale structural characterisation with robust modelling frameworks is proposed as a necessary foundation for a more reliable understanding of precursor behaviour, with implications for the rational design of AAMs and the expanded utilisation of diverse aluminosilicate resources.</p>