This paper discusses the process of crystallization by particle attachment in synthetic, biogenic, and geologic environments. It reviews the mechanisms and pathways of crystal growth through the addition of particles, which can range from multi-ion complexes to fully formed nanoparticles. The study highlights that classical models of crystallization, which consider only the addition of monomeric chemical species, are insufficient to explain the observed phenomena. Instead, the interplay of free-energy landscapes and reaction dynamics leads to multiple pathways for crystallization. The paper also explores the role of particle attachment in biomineral formation, where amorphous precursors transform into crystalline structures. It discusses the importance of particle-based pathways in determining the structure and properties of materials, including unique morphologies, nonequilibrium symmetries, and organic-inorganic hybrid structures. The paper also addresses the influence of surface energy on crystallization pathways and the role of precursor phases in the formation of final stable phases. It highlights the challenges in understanding the dynamics of postnucleation growth by monomers and particles, as well as the effects of extrinsic factors such as surfaces, impurities, and confinement on crystallization. The study concludes that a predictive understanding of crystallization by particle attachment is essential for advancing nanomaterials design and synthesis, as well as for understanding the complex processes involved in biogeochemical cycling and environmental remediation. The paper emphasizes the need for interdisciplinary research to decipher the complexity of particle-attachment pathways and to develop a comprehensive physical picture of crystallization that encompasses the diversity of potential pathways.This paper discusses the process of crystallization by particle attachment in synthetic, biogenic, and geologic environments. It reviews the mechanisms and pathways of crystal growth through the addition of particles, which can range from multi-ion complexes to fully formed nanoparticles. The study highlights that classical models of crystallization, which consider only the addition of monomeric chemical species, are insufficient to explain the observed phenomena. Instead, the interplay of free-energy landscapes and reaction dynamics leads to multiple pathways for crystallization. The paper also explores the role of particle attachment in biomineral formation, where amorphous precursors transform into crystalline structures. It discusses the importance of particle-based pathways in determining the structure and properties of materials, including unique morphologies, nonequilibrium symmetries, and organic-inorganic hybrid structures. The paper also addresses the influence of surface energy on crystallization pathways and the role of precursor phases in the formation of final stable phases. It highlights the challenges in understanding the dynamics of postnucleation growth by monomers and particles, as well as the effects of extrinsic factors such as surfaces, impurities, and confinement on crystallization. The study concludes that a predictive understanding of crystallization by particle attachment is essential for advancing nanomaterials design and synthesis, as well as for understanding the complex processes involved in biogeochemical cycling and environmental remediation. The paper emphasizes the need for interdisciplinary research to decipher the complexity of particle-attachment pathways and to develop a comprehensive physical picture of crystallization that encompasses the diversity of potential pathways.