The present paper studies grain growth in the presence of inert particles by performing large-scale simulations using a parallel Monte Carlo Potts model. The effect of the second phase particles on the grain size distribution (GSD) is analyzed. The GSDs diverge markedly from the log-normal distribution for normal grain growth. For low volume fractions of particles, we find that the grain size distributions approach log-normal as stagnation takes hold. For the cases with a high volume fraction of particles, however, medium-size grains reach the log-normal distribution but both the lower and upper tails strongly diverge from the log-normal distribution over time.