Detection of Weak Lensing in the HST Survey Strip Edward J. Groth, March 16, 2001 Abstract: Brief introductions to gravitational lensing and weak lensing are given. A method for using HST WFPC2 images to investigate weak lensing is described. The method is applied to the HST Survey Strip where weak lensing is produced by the dark matter in large scale structure rather than individual objects such as large clusters. This "cosmic shear" is detected at the 99.5% confidence level. The magnitude of the shear is consistent with dark matter estimates from cluster abundances.