Fast Magnetic Reconnection is currently regarded as an important process also beyond the so-
lar system, specially in magnetically dominated regions of galactic and extragalactic sources like
the surrounds of black holes and relativistic jets. In this lecture we discuss briefly the theory of
fast magnetic reconnection, specially when driven by turbulence which is very frequent in Astro-
physical flows, and its implications for relativistic particle acceleration. Then we discuss these
processes in the context of the sources above, showing recent analytical and multidimensional nu-
merical MHD studies that indicate that fast reconnection can be a powerful process to accelerate
particles to relativistic velocities, produce the associated high energy non-thermal emission, and
account for efficient conversion of magnetic into kinetic energy in these flows.