The 7-year WMAP data, combined with improved astrophysical data, rigorously tests the standard cosmological model and provides new constraints on its parameters. The analysis determines the parameters of the simplest 6-parameter ΛCDM model, with the primordial power spectrum index n_s = 0.968 ± 0.012, excluding the Harrison-Zel'dovich-Peebles spectrum at 99.5% confidence. Other parameters are consistent with and improved from 5-year results. The 7-year temperature power spectrum improves the determination of the third acoustic peak, leading to a better estimate of the matter-radiation equality epoch. Improved parameters include the total neutrino mass (sum m_ν < 0.58 eV) and the effective number of neutrino species (N_eff = 4.34 ± 0.86). The dark energy equation of state parameter w is constrained to -1.10 ± 0.14 (68% CL) without high-redshift supernovae. The WMAP data detect the effect of primordial helium on the temperature power spectrum, measuring Y_p = 0.326 ± 0.075 (68% CL). The data also detect tangential and radial polarization patterns around temperature fluctuations, confirming adiabatic scalar fluctuations. The 7-year polarization data improve the detection of the temperature-E-mode cross power spectrum to 21σ, and the temperature-B-mode cross power spectrum to a 38% improved limit on polarization rotation. The WMAP data detect the Sunyaev-Zel'dovich effect in known galaxy clusters, with results consistent with X-ray data but lower than theoretical predictions. The data show a significant difference between cooling-flow and non-cooling-flow clusters, explaining some discrepancies. The WMAP data also provide new insights into the cosmic microwave background polarization, confirming the standard model's predictions. The analysis improves constraints on cosmological parameters, including the Hubble constant, dark energy, and neutrino mass. The results are consistent with the standard model and provide new insights into the early universe and cosmological parameters.The 7-year WMAP data, combined with improved astrophysical data, rigorously tests the standard cosmological model and provides new constraints on its parameters. The analysis determines the parameters of the simplest 6-parameter ΛCDM model, with the primordial power spectrum index n_s = 0.968 ± 0.012, excluding the Harrison-Zel'dovich-Peebles spectrum at 99.5% confidence. Other parameters are consistent with and improved from 5-year results. The 7-year temperature power spectrum improves the determination of the third acoustic peak, leading to a better estimate of the matter-radiation equality epoch. Improved parameters include the total neutrino mass (sum m_ν < 0.58 eV) and the effective number of neutrino species (N_eff = 4.34 ± 0.86). The dark energy equation of state parameter w is constrained to -1.10 ± 0.14 (68% CL) without high-redshift supernovae. The WMAP data detect the effect of primordial helium on the temperature power spectrum, measuring Y_p = 0.326 ± 0.075 (68% CL). The data also detect tangential and radial polarization patterns around temperature fluctuations, confirming adiabatic scalar fluctuations. The 7-year polarization data improve the detection of the temperature-E-mode cross power spectrum to 21σ, and the temperature-B-mode cross power spectrum to a 38% improved limit on polarization rotation. The WMAP data detect the Sunyaev-Zel'dovich effect in known galaxy clusters, with results consistent with X-ray data but lower than theoretical predictions. The data show a significant difference between cooling-flow and non-cooling-flow clusters, explaining some discrepancies. The WMAP data also provide new insights into the cosmic microwave background polarization, confirming the standard model's predictions. The analysis improves constraints on cosmological parameters, including the Hubble constant, dark energy, and neutrino mass. The results are consistent with the standard model and provide new insights into the early universe and cosmological parameters.