The chapters of this dissertation explore the theoretical and empirical potential of neural networks and deep learning as estimation techniques in economics. The first chapter provides a novel approximation result for two hidden layer neural networks that makes clear the trade-off between width and depth. I leverage this result to provide consistency and $o_p(n^{-1/4})$ convergence rates for this estimator and demonstrate its flexibility in finite samples. In addition, I introduce a new algorithm called cross-training that allows construction of asymptotic confidence intervals for linear functionals. In the second chapter I provide a new neural network designed for a panel data setting with a common index. I allow for unobserved heterogenei...