An option pricing model that involves the construction of a binomial tree to show the different paths that the underlying asset may take over the option's life. A lattice model can take into account expected changes in various parameters such as volatility over the life of the options, providing more accurate estimates of option prices than the Black-Scholes model. The lattice model is particularly suited to the pricing of employee stock options, which have a number of unique attributes. The lattice model's flexibility in incorporating expected volatility changes is especially useful in certain circumstances, such as pricing employee options at early-stage companies. Such companies may expect lower volatility in their stock prices in the future as their businesses mature. This assumption can be factored into a lattice model, enabling more accurate option pricing than the Black-Scholes model, which inputs the same level of volatility over the life of the option.