Let E/Q be an elliptic curve and p a prime of good reduction. Iwasawa Theory allows us to prove that the Mordell-Weil rank of E is finite over the Zp-cyclotomic extension of Q. In this talk, I will review some of the techniques involved in this proof and explain how similar ideas can be used to estimate the growth of Mordell-Weil ranks inside the Zp^2-extension of an imaginary quadratic field.