ULTRA-COMPACT BINARIES ARE ONE OF THE MAJOR CLASSES OF SOURCES DETECTABLE BY LISA. THE NUMBER OF SUCH SOURCES IS ESTIMATED TO BE VERY LARGE -- MORE THAN 10 000 INDIVIDUALLY DETECTABLE SOURCES AND AN EVEN LARGER NUMBER OF SOURCES CONTRIBUTING TO (AND DOMINATING) THE LISA BACKGROUND BELOW ABOUT 2 MHZ. MUCH REMAINS TO BE LEARNED ABOUT THE NATURE OF ULTRA-COMPACT BINARIES. TO DATE ONLY A HAND-FULL OF LISA VERIFICATION SOURCES HAVE BEEN IDENTIFIED AND THE TOTAL NUMBER OF KNOWN BINARIES WITH PERIODS LESS THAN 60 MINUTES IS ONLY A FEW DOZEN. THE ZWICKY TRANSIENT FACILITY (ZTF) IS A MAJOR NEW LARGE-AREA GROUND-BASED OPTICAL SURVEY INSTRUMENT HAVING JUST BEGUN SURVEY OBSERVATIONS IN MAY-JUNE 2019. ZTF WILL LIKELY BE THE MOST POWERFUL NEAR-TERM INSTRUMENT FOR DETECTION AND CHARACTERIZATION OF ULTRA-COMPACT BINARIES AT LEAST UNTIL LSST BECOMES AVAILABLE. COMBINED WITH GAIA SOURCE DISTANT ESTIMATES ZTF WILL SIGNIFICANTLY INCREASE THE NUMBER OF KNOWN LISA VERIFICATION BINARIES AS WELL AS DETECT HUNDREDS OF OTHER COMPACT BINARIES THAT WILL PROVIDE A DEEPER UNDERSTANDING OF THE ASTROPHYSICS OF THE VARIOUS BINARY CHANNELS THAT WILL CONTRIBUTE TO THE LISA GW SIGNAL. THE PROPOSED WORK INVOLVES OBSERVATIONAL DETECTION AND CHARACTERIZATION OF ZTF IDENTIFIED COMPACT BINARIES. OUR PROPOSAL TEAM INCLUDES OBSERVERS EXPERIENCED IN TIME-DOMAIN ANALYSIS AS WELL AS CONSULTANT THEORISTS.