Guinan and DeWarf, with M. Güdel (PSI & ETHZ, Switzerland) and J.D. Dorren (Edinburgh, Scot.), continue with the Sun in Time project, a coordinated multiwavelength study of several nearby, single, solar-type stars selected as proxies for the Sun at several stages in its evolution from ZAMS (Zero Age Main-Sequence) to TAMS (Terminal Age Main-Sequence). An extensive body of ultraviolet (IUE), and X-ray (Einstein and ROSAT) observations of late-type stars is employed to investigate the coronal, transition-region (TR), and chromospheric emission of single solar-type stars with spectral types close to solar. By considering only main-sequence stars in a restricted range of spectral types (F5 V - G8 V) with measured rotation periods, they can focus on the role of rotation in determining activity levels, since the exclusion of K stars significantly limits the variation range of other properties such as mass, radius, temperature and, particularly, convection zone depth. There is still a wide spread of rotation rates (P days) and ages (70 Myr to 9.5 Gyr), and consequently a wide range of magnetic activity. These stars thus constitute a test of the effect on the stellar dynamo of varying the rotation rate, keeping all other parameters approximately constant. They have derived precise relations between X-ray (corona), C IV (transition region), and Mg II (chromosphere) emission and rotation period for stars in this range of spectral types. Moreover, there appears to be little difference in the relations obeyed by the entire group and those of the subset of G0 V - G5 V stars that are very close to solar. Since this smaller group may be considered to be proxies for the Sun at different ages, they have, in effect, also determined empirical relationships between the historical solar magnetic activity (coronal, TR, and chromospheric) and the Sun's rotation period, which is related to solar age. These results have been combined with existing rotation-age relations to obtain rotation-activity-age relations. In addition, photoelectric photometry of several of these stars shows a correlation between the mean light curve amplitude and the rotation period, which indicates how the photospheric (starspot) activity (areal extent) depends on rotation. The use of rotation period rather than projected rotational velocity significantly reduces the uncertainties in these relations.