  We present results of an investigation of the X-ray properties, age
distribution, and kinematical characteristics of a high-galactic latitude
sample of late-type field stars selected from the ROSAT All-Sky Survey (RASS).
The sample comprises 254 RASS sources with optical counterparts of spectral
types F to M distributed over six study areas located at |b| >= 20 degr, and
DEC >= -9 degr. A detailed study was carried out for the subsample of ~200 G,
K, and M stars. Lithium abundances were determined for 179 G-M stars. Radial
velocities were measured for most of the 141 G and K type stars of the sample.
Combined with proper motions these data were used to study the age distribution
and the kinematical properties of the sample. Based on the lithium abundances
half of the G-K stars were found to be younger than the Hyades (660 Myr). About
25% are comparable in age to the Pleiades (100 Myr). A small subsample of 10
stars is younger than the Pleiades. They are therefore most likely pre-main
sequence stars. Kinematically the PMS and Pleiades-type stars appear to form a
group with space velocities close to the Castor moving group but clearly
distinct from the Local Association.
