The pre-main sequence evolutionary models of low mass stars in the mass range 0.30 Msun - 0.60 Msun.

Evolutionary models of stars of low mass in the mass range of 0.30 to 0.60 solar masses are presented. Each model begins from the threshold of stability and the evolution progresses up to the zero age main sequence (ZAMS). Particular attention has been paid to the treatment of the electron screening factors and thermonuclear reaction rates. A comparison for the effects of new opacity values and the ones used in this study is also given.