Lithium insertion in anatase is studied by considering simultaneously the effects of crystallinity and surface area on storage mechanism, namely intercalation vs. pseudocapacitive. 6 nm anatase crystallites with high surface area (222 m2 g−1), synthesized via a novel continuous aqueous process and annealed at different temperatures (200 °C, 300 °C, and 400 °C), were electrochemically tested. By annealing, crystallinity was increased, while surface area decreased allowing for the investigation of the contributions of each toward lithiation and delithiation behavior. The as-synthesized and best-annealed (at 300 °C) samples were compared at various rates. At low rate (1C and 2C) the annealed anatase had higher reversible capacity than the as-synthesized, due to increased diffusion-based storage. At high rate however, as-synthesized anatase had much higher capacity due to increased surface area and ability to store Li-ions pseudocapacitively. Increased crystallinity leads to increased diffusivity as determined by electrochemical impedance spectroscopy, explaining why the 300 °C anneal had higher capacity at low rate. Long-term cycling at high rate, however, showed that reliance on diffusion-based storage (intercalation) in the case of the 300 °C anneal causes increased polarization that leads to electrode performance decline. These results point to the importance of simultaneous nanoanatase property (crystallinity and surface area) optimization for achieving stable performance.