From a detailed examination of all stars with known proper motion and radial velocity, approximately 200 stars and binary systems, in addition to the known members of the Hyades and Praesepe clusters, have been selected as probable members of the Hyades group. The (Mv, B - V)-diagram for less than 50 per cent of these stars for which accurate magnitudes and colours are available shows (i) that evolution in the group has reached stars with Mr +2m, (z) awell-definedHertzsprunggap (B- V +0m.35 to + ) between Mv= +o .5 and + 1m.5 with the prototype variable Scu and the peculiar stars ft CrB and y Cap on the blue edge of the gap, and (3) that, in corumon with most well-observed clusters, there are at least two group members still on or near the main sequence well above the break-off point - CVn and y Cen. A comparison between the group and trigonometric parallaxes shows no large systematic error in the latter and confirms the high weight usually given the determinations made at the Allegheny Observatory. The space distribution of the group members indicates that (a) there are probably many undiscovered members near the Sun in the Southern Hemisphere and (b) the group may be elongated in the direction of galactic rotation. The correlation between the velocity of the individual group members perpendicular to the galactic plane and their distance from that plane indicates that this motion may be uncoupled from that in the plane. More than 50 per cent of the stars selected as group members have at least one known companion. The sixteen main sequence binaries with known orbital elements are found to deviate more from the normal mass- luminosity relation than the two giant systems in the group, Aur and y Cen. There are several eclipsing binaries among the group members but complete data are available for only TX Cnc, in the Praesepe cluster, and Z Her. The primary component of Z Her may be a normal main sequence star but the companion is a late-type subgiant which is evolutive.