Catheter apparatuses, systems, and methods for achieving renal neuromodulation by intravascular access are disclosed herein. One aspect of the present technology, for example, is directed to a treatment device having a multi-electrode array configured to be delivered to a renal blood vessel. The array is selectively transformable between a delivery or low-profile state (e.g., a generally straight shape) and a deployed state (e.g., a radially expanded, generally helical shape). The multi-electrode array is sized and shaped so that the electrodes or energy delivery elements contact an interior wall of the renal blood vessel when the array is in the deployed (e.g., helical) state. The electrodes or energy delivery elements are configured for direct and/or indirect application of thermal and/or electrical energy to heat or otherwise electrically modulate neural fibers that contribute to renal function or of vascular structures that feed or perfuse the neural fibers.