Using flow shadowgraph and schlieren photographs obtained from the Naval Ordnance Laboratory's ballistics ranges, measurements have been made of the widths of the laminar wakes, their lengths (wake transition distances), and the subsequent growth of the turbulent wakes of both pointed and blunt slender cones. The laminar wake width and transition dis- tance measurements include the effects of base rounding. Correlations of laminar wake width with transition Reynolds number are shown. Transition Reynolds numbers of cones with rounded bases are larger for Mm > 12 than those for cones with flat bases. Moderate nose bluntness and change in nose shape have no measurable effects on laminar wake width or wake transition distance. An empirical wake growth function appears to be related to laminar wake width and transition distance functions. HEN the boundary layer on a hypersonic axisymmetric body is laminar, laminar-turbulent transition occurs in the wake flow region downstream of the neck. At present, no adequate theoretical method exists for the solution of the axisymmetric laminar wake stability problem and subsequent prediction of the transition location. Therefore, correlations of experimental data in terms of freestream parameters or computed flowfield properties should be of value. This paper presents results of an investigation of the effects of three factors on wake transition: laminar wake width, nose shape and bluntness, and the rounding of the base expansion corner of the pointed-cone models. Measurements of widths and lengths of laminar wrakes were made from shadowgraphs resulting from tests conducted for the General Electric Com- pany in the ballistics ranges at Naval Ordnance Laboratory (NOL). Only rounds with low angle of attack, as determined in orthogonal planes, have been used. The laminar wake has a virtually constant thickness from the neck to the transition point. After transition, the wake grows by turbulent diffu- sion. Measurements of turbulent wake width of both pointed- and blunt-cone models have been made on shadow- graphs and schlieren photographs. The measurement at any axial station has been the average of the maximum and mini- mum wake width in the immediate region of the point. Only shots with low angle of attack, as determined in orthogo- nal planes, have been used. Many previous studies13 of turbulent wake growth of spheres and cones have been made; however, their emphasis has been on the far wake growth, ignoring the transitional region. The purpose of this present study is to examine the transitional region to determine how laminar wake character- istics affect turbulent wake growth and how the laminar and turbulent regions can be related. Toward this end, meas- urements have been made in the region 0 < x/d < 100.