Trade and development enthusiasts will find plenty of reading material in the NBER’s latest batch of working papers. David Hummels, Volodymyr Lugovskyy & Alexandre Skiba argue that price discrimination in the shipping industry reduces developing country trade flows. Elhanan Helpman, Marc Melitz & Yona Rubinstein present a model of heterogeneous firms that results in a generalized gravity equation that accounts for the self-selection of firms into export markets and their impact on trade volumes (older version here). Eric V. Edmonds summarizes empirical work on child labor (ungated pdf here).