Theoretical modeling of the expansion of hydraulic fractures has proceeded on three fronts: (i) blanket sand, no leakoff, fracture shape assumed, (ii) blanket sand, includes leakoff, fracture shape derived, (iii) lenticular sand. As a continuation of the last annual report, (1) assumes the fracture perimeter is an ellipse, then solves the governing equations (without leakoff) to obtain fracture height at the wellbore in two models, FL1 and FL2, for the case of a payzone bounded by two zones of higher (but equal) minimum in-situ stress. The two models describe the variation of minimum in-situ stress in the vertical direction differently. Subsequent modeling in (ii) indicates that the results here are a good approximation for the case in which the fracture shape and fluid flow profile are derived, rather than assumed. In a parameter study, the wellbore height and pressure are investigated as to the way they depend upon stress contrast between pay and bounding zones, elastic modulus of the formation (assumed the same in each zone), height of the payzone, and finally, fracture toughness in the bounding zones. To improve the accuracy of the modeling, in (ii) leakoff is included and the assumption of elliptical fracture shape is discarded. A complete, illustrative solution is given for fracture height, shape, and bottomhole pressure. The main limitation of the models in (i) and (ii) is that rate of height growth must be considerabl less than rate of length expansion. Finally, in (iii) some preliminary modeling of fracture expansion in lenticular gas sands is presented. 19 figures, 1 table.