We report enhanced thermoelectric performance in SnTe, where significantly improved electrical transport properties and reduced thermal conductivity were achieved simultaneously. The former was obtained from a larger hole Seebeck coefficient through Fermi level tuning by optimizing < 0.2 the carrier concentration with Ga, In, Bi, and Sb dopants, resulting in a power factor of mu W cm(-1) K-2 and ZT of 0.9 at 823 K in Sn0.97Bi0.03.Te.. To reduce the lattice thermal conductivity without deteriorating the hole carrier mobility in Sn0.97Bi0.03Te, SrTe was chosen as the second phase to create strained endotaxial nanostructures as phonon scattering centers. As a result, the lattice thermal conductivity decreases strongly from similar to 2.0 Wm(-1) K-1 for Sn0.97Bi0.03Te to X1.2 Wm(-1) as the SrTe content is increased from 0 to 5.0% at room temperature and from similar to 1.1 to -,0.70 Wm-1 IC' at 823 K. For the Sn0.97Bi0.03Te-3% SrTe sample, this leads to a ZT of 1.2 at 823 K and a high average ZT (for SnTe) of 0.7 in the temperature range of 300-823 K, suggesting that SnTe is a robust candidate for medium temperature thermoelectric applications.