The 7-year Wilkinson Microwave Anisotropy Probe (WMAP) observations, combined with improved astrophysical data, rigorously test the standard cosmological model and place new constraints on its parameters. By integrating the WMAP data with Baryon Acoustic Oscillation (BAO) measurements from galaxy distributions and the Hubble constant ($H_0$), the parameters of the simplest 6-parameter $\Lambda$CDM model are determined. The power-law index of the primordial power spectrum is $n_s = 0.968 \pm 0.012$ (68% CL), excluding the Harrison-Zel'dovich-Peebles spectrum by 99.5% CL. Other parameters, including those beyond the minimal set, are consistent with and improved from the 5-year results. No convincing deviations from the minimal model are found. The 7-year temperature power spectrum provides a better determination of the third acoustic peak, improving the measurement of the redshift of the matter-radiation equality epoch. Notable improvements include the total mass of neutrinos, $\sum m_\nu < 0.58$ eV (95% CL), and the effective number of neutrino species, $N_{\text{eff}} = 4.34^{+0.86}_{-0.88}$ (68% CL). The limit on the constant dark energy equation of state parameter from WMAP+BAO+$H_0$ is $w = -1.10 \pm 0.14$ (68% CL). The effect of primordial helium on the temperature power spectrum is detected, and a new test of big bang nucleosynthesis is provided by measuring $Y_p = 0.326 \pm 0.075$ (68% CL). The tangential and radial polarization patterns around hot and cold spots of temperature fluctuations are detected for the first time, providing an important test of physical processes at $z = 1090$ and the dominance of adiabatic scalar fluctuations. The 7-year polarization data significantly improve, with the temperature-$E$-mode polarization cross power spectrum detected at $21\sigma$, compared to $13\sigma$ from the 5-year data. The limit on a rotation of the polarization plane due to potential parity-violating effects improves by 38% to $\Delta\alpha = -1.1^{\circ} \pm 1.4^{\circ}$ (statistical) $\pm 1.5^{\circ}$ (systematic) (68% CL). Significant detections of the Sunyaev-Zel'dovich (SZ) effect at the locations of known galaxy clusters are reported, with the measured SZ signal agreeing well with the expected signal from X-ray data on a cluster-by-cluster basis. However, it is aThe 7-year Wilkinson Microwave Anisotropy Probe (WMAP) observations, combined with improved astrophysical data, rigorously test the standard cosmological model and place new constraints on its parameters. By integrating the WMAP data with Baryon Acoustic Oscillation (BAO) measurements from galaxy distributions and the Hubble constant ($H_0$), the parameters of the simplest 6-parameter $\Lambda$CDM model are determined. The power-law index of the primordial power spectrum is $n_s = 0.968 \pm 0.012$ (68% CL), excluding the Harrison-Zel'dovich-Peebles spectrum by 99.5% CL. Other parameters, including those beyond the minimal set, are consistent with and improved from the 5-year results. No convincing deviations from the minimal model are found. The 7-year temperature power spectrum provides a better determination of the third acoustic peak, improving the measurement of the redshift of the matter-radiation equality epoch. Notable improvements include the total mass of neutrinos, $\sum m_\nu < 0.58$ eV (95% CL), and the effective number of neutrino species, $N_{\text{eff}} = 4.34^{+0.86}_{-0.88}$ (68% CL). The limit on the constant dark energy equation of state parameter from WMAP+BAO+$H_0$ is $w = -1.10 \pm 0.14$ (68% CL). The effect of primordial helium on the temperature power spectrum is detected, and a new test of big bang nucleosynthesis is provided by measuring $Y_p = 0.326 \pm 0.075$ (68% CL). The tangential and radial polarization patterns around hot and cold spots of temperature fluctuations are detected for the first time, providing an important test of physical processes at $z = 1090$ and the dominance of adiabatic scalar fluctuations. The 7-year polarization data significantly improve, with the temperature-$E$-mode polarization cross power spectrum detected at $21\sigma$, compared to $13\sigma$ from the 5-year data. The limit on a rotation of the polarization plane due to potential parity-violating effects improves by 38% to $\Delta\alpha = -1.1^{\circ} \pm 1.4^{\circ}$ (statistical) $\pm 1.5^{\circ}$ (systematic) (68% CL). Significant detections of the Sunyaev-Zel'dovich (SZ) effect at the locations of known galaxy clusters are reported, with the measured SZ signal agreeing well with the expected signal from X-ray data on a cluster-by-cluster basis. However, it is a