Equivalent width of Hα vs. effective temperature. The color − codes refer to the Spitzer YSO classes: Class III (green; light gray in b/w print), Class II/III (blue; dark gray in b/w print), Class II (red; medium gray in b/w print) and Class I (yellow and larger). Different mass ranges are symbolized with different plotting symbols: 0.1−0.25   M_⊙ (star symbols), 0.25−0.6   M_⊙ (circles), 0.6−1.2   M_⊙ (triangles) and all others (squares). Vertical lines connect different epochs of W_Hα measurements for individual stars. The black line separates accreting cTTS (top) from non-accreting wTTS (bottom). The cross on the black line denotes spectral type M6. For objects with T_eff smaller than this value White & Basri (2003) have placed the dividing line between cTTS and wTTS at 40 Å. However, our boundary of 20 Å agrees better with the separation of Class II and Class III sources.