Concerns with decreasing productivity and increasing survey costs are leaving many surveys to consider abandoning their historic use of RDD and CATI for the seemingly greener pastures of ABS and mixed mode data collection involving web response. But such drastic design changes must be carefully considered when studies involve lengthy interviews, multiple survey languages, diverse target populations, and several interviews within a single household. This presentation shares results from two California Health Interview Survey (CHIS) field experiments using an ABS sequential mixed-mode design: mail invitation push-to-web with a CATI nonresponse follow-up. The field experiments included many imbedded methodological experiments including 1) differing mail classes for final invitations, 2) language-directed invitations, 3) multiple within-household selection procedures, 4) random interview order for adult and child surveys, 5) differential incentives for obtaining permission from parents to interview teens, and 6) multi-mode contact strategies to interview teens. We examine response rates, cost differences, and shifts in key estimates compared to CHIS production data. In general, the revised design makes large strides to improve response rates and reduce costs per complete for CHIS, but numerous shifts in key estimates could disrupt historic trends, and some challenges remain for effectively representing some major racial and ethnic minorities within the state.