This thesis investigates topics in consumption and labor supply using "big" data from bank accounts and credit cards from personal financial records. Chapter 1 discusses how these data allow researchers to examine economic activity in gig economy jobs, a sector has been difficult to measure due to lack of data. Chapter 2 focuses on one popular gig economy industry, ridesharing, to explore whether flexible work can help workers better smooth their consumption. Chapter 3 examines how these data can be used to measure the marginal propensity to consume out of permanent shocks by exploiting changes in gasoline prices.