The performance of pavement depends to a large extent on the strength of subgrade. Subgrade should be strong enough to take up the stresses imposed due to loads without shear failure and excessive deformation. Subgrade layer consisting of clay-sand-gravel mixture is advisable for all types of substructure condition. Subgrade soil strength is evaluated in terms of California Bearing Ratio (CBR) and is used in design of flexible pavement. This paper describes the influence of clay content on compaction characteristics, unsoaked CBR values, and undrained shear parameters of clay-sand-gravel mixture. Experiments were conducted on nine different mixtures of clay-sand-gravel under heavy compaction characteristics to measure unsoaked CBR and shear parameters. Clay-sand-gravel mixtures were prepared by mixing clay content to mixture of sand and gravel in varying percentage from 10 to 50% at the increment of 5% by weight. Sand and gravel were mixed in equal proportion by weight. The influence of clay percentage, dry density and moisture content on CBR, cohesion and angle of friction was examined. A functional relationship has been identified to estimate CBR of clay-sand-gravel mixtures. Using multiple linear regression analysis, a relationship is proposed to estimate CBR of clay-sand-gravel mixtures under unsoaked conditions. Based on multiple linear regression analysis, statistical assessment is done to predict the behavior of the variables on CBR. The presented experimental works as well as statistical results are useful in assessing and predicting the performance of subgrade layer in pavement construction.