It has long been recognized that the development rate and yield of soybean are sensitive to temperature and photoperiod. This chapter considers a range of experimental evidence concerning the precise effects of these factors on soybean reproductive development, and reviews ten diverse methods of mathematically modelling these effects. In the course of this discussion, several scientific questions are raised, such as whether the photoperiod effect exists in post-flowering stages, and what the nature of such an effect might be. It is concluded that quantitative research of integrated modelling and experimentation at gene level may hold the key to improving the modelling of temperature and photoperiod effects on soybean development.