[en] We present a model for the $[\mathrm{\alpha <!--\; ??\; -->}/\mathrm{F}\mathrm{e}]\text{--}[\mathrm{F}\mathrm{e}/\mathrm{H}]$ distribution of stars in the inner Galaxy, $3\mathrm{k}\mathrm{p}\mathrm{c}<<!--\; <\; -->R<<!--\; <\; -->5\mathrm{k}\mathrm{p}\mathrm{c}$, measured as a function of vertical distance $|z|$ from the midplane by Hayden et al. (H15). Motivated by an “upside-down” scenario for thick disk formation, in which the thickness of the star-forming gas layer contracts as the stellar mass of the disk grows, we combine one-zone chemical evolution with a simple prescription in which the scale-height of the stellar distribution drops linearly from $z_h=0.8\mathrm{k}\mathrm{p}\mathrm{c}$ to $z_h=0.2\mathrm{k}\mathrm{p}\mathrm{c}$ over a timescale t _c, remaining constant thereafter. We assume a linear-exponential star formation history, ${\stackrel{\dot{}<!--\; ??\; -->}{M}}_{\ast <!--\; ???\; -->}(t)\propto <!--\; ???\; -->{te}^{-<!--\; ???\; -->t/t_{\mathrm{s}\mathrm{f}}}$. With a star formation efficiency timescale ${\mathrm{\tau <!--\; ??\; -->}}_{\ast <!--\; ???\; -->}=M_g(t)/{\stackrel{\dot{}<!--\; ??\; -->}{M}}_{\ast <!--\; ???\; -->}(t)=2\mathrm{G}\mathrm{y}\mathrm{r}$, an outflow mass-loading factor $\mathrm{\eta <!--\; ??\; -->}={\stackrel{\dot{}<!--\; ??\; -->}{M}}_{\mathrm{o}\mathrm{u}\mathrm{t}}(t)/{\stackrel{\dot{}<!--\; ??\; -->}{M}}_{\ast <!--\; ???\; -->}(t)=1.5$, $t_{\mathrm{s}\mathrm{f}}=3\mathrm{G}\mathrm{y}\mathrm{r}$, and $t_c=2.5\mathrm{G}\mathrm{y}\mathrm{r}$, the model reproduces the observed locus of inner disk stars in $[\mathrm{\alpha <!--\; ??\; -->}/\mathrm{F}\mathrm{e}]\text{--}[\mathrm{F}\mathrm{e}/\mathrm{H}]$ and the metallicity distribution functions (MDFs) measured by H15 at $|z|=0\text{--}0.5\mathrm{k}\mathrm{p}\mathrm{c}$, $0.5\text{--}1\mathrm{k}\mathrm{p}\mathrm{c}$, and $1\text{--}2\mathrm{k}\mathrm{p}\mathrm{c}$. Substantial changes to model parameters lead to disagreement with the H15 data; for example, models with $t_c=1\mathrm{G}\mathrm{y}\mathrm{r}$ or $t_{\mathrm{s}\mathrm{f}}=1\mathrm{G}\mathrm{y}\mathrm{r}$ fail to match the observed MDF at high-$|z|$ and low-$|z|$, respectively. The inferred scale-height evolution, with z _h(t) dropping on a timescale $t_c\sim <!--\; ???\; -->t_{\mathrm{s}\mathrm{f}}$ at large lookback times, favors upside-down formation over dynamical heating of an initially thin stellar population as the primary mechanism regulating disk thickness. The failure of our short-t _c models suggests that any model in which thick disk formation is a discrete event will not reproduce the continuous dependence of the MDF on $|z|$ found by H15. Our scenario for the evolution of the inner disk can be tested by future measurements of the $|z|$-distribution and the age–metallicity distribution at $R=3\text{--}5\mathrm{k}\mathrm{p}\mathrm{c}$.