There is a growing interest in improving wood properties through clonal selection. However, traditional methods for determining wood properties are difficult to implement at the scale required for large-scale selection programs. In this study, we used rapid phenotyping methods (i.e., drill resistance (DR) and stress wave velocity (SWV)) for assessing wood quality in a 3-year-old clonal trial containing 125 clonal poplar hybrids. These hybrids belong to interspecific crosses of Populus deltoides [D], P. trichocarpa [T], P. nigra [N], and P. maximowiczii [M]. We estimated clonal variation and correlations among DR, SWV, basic density (BD), and dynamic modulus of elasticity (MOEd). Clonal repeatabilities were moderate for all traits, but were higher for BD and DR (i.e., R2 = 0.45 and 0.46, respectively) than for SWV and MOEd (i.e., R2 = 0.30 and 0.35, respectively). Clonal mean phenotypic correlations were high between BD and DR (rc = 0.84) and between SWV and MOEd (0.87), and the clonal correlations (rg) were 0.90 and 0.96, respectively. Overall, there was a weak relation between BD and MOEd (rc = 0.23 and rg = 0.29, respectively). Results support the use of DR and SWV as tools for the selection of poplar clones oriented to improve solid wood properties.