The invention relates to a traction battery assembly having a snap-in bus bar module. The traction battery includes a cell having a terminal defining a surface with a top and at least one sidewall. The traction battery also includes a bus bar having an interior defining a top engaging with the top of the terminal, and at least one side surface engaging with the sidewall. One of the side surface and the sidewall includes a projection and the other of the side surface and the sidewall includes a receptacle for receiving the projection.