Devices and methods for assessing tissue contact based on dielectric properties and/or impedance sensing are disclosed. In some embodiments, one or more probing frequencies are delivered via electrodes including an electrode in proximity to a tissue (for example, myocardial tissue). In some embodiments, dielectric parameter values, optionally together with other known and/or estimated tissue characteristics, are measured to determine a contact quality with the tissue. In some embodiments, dielectric contact quality is used, for example, in guiding the formation of a lesion (for example, RF ablation of heart tissue to alter electrical transmission characteristics).