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Alfv\'enicity is a well-known property, common in the solar wind,characterized by a high correlation between magnetic and velocity fluctuations.Data from the Parker Solar Probe (PSP) enable the study of this property closerto the Sun than ever before, as well as in sub-Alfv\'enic solar wind. Weconsider scale-dependent measures of Alfv\'enicity based on second-orderfunctions of the magnetic and velocity increments as a function of time lag,including the normalized cross-helicity $\sigma_c$ and residual energy$\sigma_r$. Scale-dependent Alfv\'enicity is strongest for lags near thecorrelation scale and increases when moving closer to the Sun. We find that$\sigma_r$ typically remains close to the maximally negative value compatiblewith $\sigma_c$. We did not observe significant changes in measures ofAlfv\'enicity between sub-Alfv\'enic and super-Alfv\'enic wind. During mosttimes, the solar wind was highly Alfv\'enic; however, lower Alfv\'enicity wasobserved when PSP approached the heliospheric current sheet or other magneticstructures with sudden changes in the radial magnetic field, non-unidirectionalstrahl electron pitch angle distributions, and strong electron densitycontrasts. These results are consistent with a picture in which Alfv\'enicfluctuations generated near the photosphere transport outward forming highlyAlfv\'enic states in the young solar wind and subsequent interactions withlarge scale structures and gradients leads to weaker Alfv\'enicity, as commonlyobserved at larger heliocentric distances.

Scale and Time Dependence of Alfv\'enicity in the Solar Wind as Observed by {\it Parker Solar Probe}