Many flow applications involve the convective transport of scalar quantities, such as energy, chemical species and turbulent energy. A variety of lattice Boltzmann scalar transport methods have been developed, many based on a separate distribution function for each scalar field. A new passive scalar transport model is presented that simulates the convection contribution for all scalar fields using a single mass transfer distribution. The diffusion contribution is calculated independently. The advantages and disadvantages of this approach are discussed. The accuracy of this model is demonstrated for two transport applications.