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I present results from a monitoring campaign of 11 active galacticnuclei (AGN) conducted in Spring of 2014. I use the reverberationmapping method to probe the interior structures of the AGN,specifically the broad line regions (BLRs) and accretion disks. Oneof these AGN, NGC~5548, was also subject to multi-wavelength (X-ray,UV, optical, and near-IR) monitoring using 25 ground-based telescopesand four space-based facilities.For NGC~5548, I detect lags between the continuum emission atdifferent wavelengths that follow a trend consistent with theprediction for continuum reprocessing by an accretion disk withtemperature profile $T \propto R^{-3/4}$. However, the lags imply adisk radius that is 3 times larger than the prediction from standardthin-disk models. The lags at wavelengths longer than the {\it V}band are also equal to or greater than the lags ofhigh-ionization-state emission lines (such as He\,{\sc ii}\,$\lambda1640$ and $\lambda 4686$), suggesting that the continuum-emittingsource is of a physical size comparable to the inner broad-lineregion. Using optical spectra from the Large Binocular Telescope, Iestimate the bias of the interband continuum lags due to BLR emissionobserved in the filters, and I find that the bias for filters withhigh levels of BLR contamination ($\sim\! 20\%$) can be important forthe shortest continuum lags. This likely has a significant impact onthe {\it u} and {\it U} bands owing to Balmer continuum emission.I then develop a new procedure for the internal (night-to-night)calibration of time series spectra that can reach precisions of$\sim\! 1$ millimagnitude and improves traditional techniques by upto a factor of 5. At this level, other systematic issues (e.g., thenightly sensitivity functions and Fe{\sc ii} contamination) limit thefinal precision of the observed light curves.Using the new calibration method, I next present the data and firstresults from the optical spectroscopic monitoring component of thereverberation mapping campaign. Five AGN were sufficiently variableto measure continuum-H$\beta$ lags and super-massive black holemasses: MCG+08-11-011, NGC\,2617, NGC\,4051, 3C\,382, and Mrk\,374. Ialso obtain H$\gamma$ and \heii\ lags for all objects except 3C\,382.The \heii\ lags indicate radial stratification of the BLR, and themasses derived from different emission lines are in general agreement.The relative responsivities of these lines to continuum variations arealso in qualitative agreement with photoionization models.Finally, I measure optical continuum lags for the two most variabletargets, MCG+08-11-011 and NGC\,2617. I again find lags consistentwith geometrically thin accretion-disk models that have temperatureprofiles $T \propto R^{-3/4}$. The observed lags are larger thanpredictions based on standard thin-disk theory by factors of 3.3 forMCG+08-11-011 and 2.3 for NGC\,2617. Using a physical model, thesedifferences can be explained if the mass accretion rates are largerthan inferred from the optical continuum luminosity by a factor of 4.3in MCG+08-11-011 and a factor of 1.3 in NGC\,2617. While the X-rayvariability in NGC\,2617 precedes the UV/optical variability, the long2.6 day lag is problematic for coronal reprocessing models.