This review article discusses the current status of dielectrophoresis (DEP), covering its theory, technology, and applications. Over the past decade, more than 2000 publications have been published on DEP, with current trends indicating that the theory and technology have matured sufficiently for most efforts to focus on applying DEP to address unmet needs in areas such as biosensors, cell therapeutics, drug discovery, medical diagnostics, microfluidics, nanoassembly, and particle filtration. The dipole approximation for the DEP force acting on a particle in a nonuniform electric field has evolved to include multipole contributions, interactions with other cells and boundary surfaces, and the influence of electrical double-layer polarizations, particularly for nanoparticles. Theoretical modeling of electric field gradients generated by different electrode designs has also advanced. Advances in technology include the development of sophisticated electrode designs, new materials, and fabrication methods. Around three-quarters of the 300 or so scientific publications on DEP are now directed towards practical applications, with an increasing number of patent applications. The technology has advanced to the point where DEP can be used to manipulate nanoparticles for device and sensor fabrication. Most efforts are now directed towards biomedical applications, such as the spatial manipulation and selective separation of target cells or bacteria, high-throughput molecular screening, biosensors, immunoassays, and the artificial engineering of three-dimensional cell constructs. DEP can manipulate and sort cells without the need for biochemical labels or other bioengineered tags, and without contact to any surfaces. This opens up potentially important applications of DEP in stem cell research and therapy. The article also discusses the theory of DEP, including the derivation of the DEP force, the influence of particle inhomogeneity, conductive losses, and net charge, and the role of multipole moments in DEP. It also addresses the presence of perturbing boundaries or particles and the influence of these on DEP behavior. The article concludes with a discussion of theoretical modeling of DEP, including the analysis of the factor (E·∇)E, the use of numerical methods, and the development of analytical solutions for the electric potential in DEP devices.This review article discusses the current status of dielectrophoresis (DEP), covering its theory, technology, and applications. Over the past decade, more than 2000 publications have been published on DEP, with current trends indicating that the theory and technology have matured sufficiently for most efforts to focus on applying DEP to address unmet needs in areas such as biosensors, cell therapeutics, drug discovery, medical diagnostics, microfluidics, nanoassembly, and particle filtration. The dipole approximation for the DEP force acting on a particle in a nonuniform electric field has evolved to include multipole contributions, interactions with other cells and boundary surfaces, and the influence of electrical double-layer polarizations, particularly for nanoparticles. Theoretical modeling of electric field gradients generated by different electrode designs has also advanced. Advances in technology include the development of sophisticated electrode designs, new materials, and fabrication methods. Around three-quarters of the 300 or so scientific publications on DEP are now directed towards practical applications, with an increasing number of patent applications. The technology has advanced to the point where DEP can be used to manipulate nanoparticles for device and sensor fabrication. Most efforts are now directed towards biomedical applications, such as the spatial manipulation and selective separation of target cells or bacteria, high-throughput molecular screening, biosensors, immunoassays, and the artificial engineering of three-dimensional cell constructs. DEP can manipulate and sort cells without the need for biochemical labels or other bioengineered tags, and without contact to any surfaces. This opens up potentially important applications of DEP in stem cell research and therapy. The article also discusses the theory of DEP, including the derivation of the DEP force, the influence of particle inhomogeneity, conductive losses, and net charge, and the role of multipole moments in DEP. It also addresses the presence of perturbing boundaries or particles and the influence of these on DEP behavior. The article concludes with a discussion of theoretical modeling of DEP, including the analysis of the factor (E·∇)E, the use of numerical methods, and the development of analytical solutions for the electric potential in DEP devices.