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We present the first year of Hubble Space Telescope imaging of the uniquesupernova (SN) 'Refsdal', a gravitationally lensed SN at z=1.488$\pm$0.001 withmultiple images behind the galaxy cluster MACS J1149.6+2223. The first fourobserved images of SN Refsdal (images S1-S4) exhibited a slow rise (over ~150days) to reach a broad peak brightness around 20 April, 2015. Using a set oflight curve templates constructed from SN 1987A-like peculiar Type II SNe, wemeasure time delays for the four images relative to S1 of 4$\pm$4 (for S2),2$\pm$5 (S3), and 24$\pm$7 days (S4). The measured magnification ratiosrelative to S1 are 1.15$\pm$0.05 (S2), 1.01$\pm$0.04 (S3), and 0.34$\pm$0.02(S4). None of the template light curves fully captures the photometric behaviorof SN Refsdal, so we also derive complementary measurements for theseparameters using polynomials to represent the intrinsic light curve shape.These more flexible fits deliver fully consistent time delays of 7$\pm$2 (S2),0.6$\pm$3 (S3), and 27$\pm$8 days (S4). The lensing magnification ratios aresimilarly consistent, measured as 1.17$\pm$0.02 (S2), 1.00$\pm$0.01 (S3), and0.38$\pm$0.02 (S4). We compare these measurements against published predictionsfrom lens models, and find that the majority of model predictions are in verygood agreement with our measurements. Finally, we discuss avenues for futureimprovement of time delay measurements -- both for SN Refsdal and for otherstrongly lensed SNe yet to come.

SN Refsdal : Photometry and Time Delay Measurements of the First Einstein Cross Supernova