UBVRI and Hα photometry of the young open cluster NGC 6530

New UBVRI and H alpha photometry has been obtained for the young open cluster NGC 6530 located 10' east of the Lagoon Nebula (M8). We found 37 pre-main-sequence (PMS) stars with Ha emission and nine PMS candidates using the R-H alpha color, a measure of H alpha emission. From this new photometry we derived the cluster parameters (V-0 - M-V = 11.25 +/- 0.1 mag and [E(B-V)] = 0.35 mag), typical age (1.5 Myr), and an age spread of about 5 Myr. We confirmed the presence of a small amount of differential reddening across the cluster. We also verified the abnormal reddening law for the cluster, especially for a heavily embedded O7 V star, Herschel 36. Comparisons were made for several PMS evolution models with regard to the resulting age distribution and the initial mass function.