  Probing neutrinoless double beta decay is one of the primary goals for SNO+,
SNOLAB's multi-purpose neutrino detector. In order to achieve this goal the SNO
detector has been adapted so that it can be filled with Te-loaded liquid
scintillator. During the initial double beta phase the target loading is 0.3%
natural Te, which equates to $\sim790$ kg of double beta isotope. Estimating
the sensitivity to neutrinoless double beta decay requires a well understood
background model. For SNO+ this is provided by a comprehensive study
considering all possible background contributions, whether they originate from
within the liquid scintillator cocktail, the surrounding parts of the detector
or other irreducible backgrounds. Given these considerations, for five years
running in the initial phase, the expected sensitivity is
$T_{1/2}^{0\nu\beta\beta} = 9.4\times10^{25}$ at 90% CL. In these proceedings
we introduce the Majoron-emitting neutrinoless double beta decay modes, to
which SNO+ may also be sensitive.
